"None of my friends want an implant because they're scared of getting it cut out," says Estelle, 18. "I don't use the pill because a friend of mine did and it messed up her periods. The injection? Just ... noooooo! My friend had it, and it was horrible – I hate needles. The coil? That's just weird."

Estelle relies on condoms for contraception. Although good for lowering the risk of contracting an STI (sexually transmitted infection), condoms are one of the least reliable contraceptive methods available. She's been having sex for less than a year – has she ever had a conversations with a health professionals about how to avoid getting pregnant?

"I mainly just talk to my friends about it," she says. Has she ever thought she might be pregnant? "Yes."

So does she think condoms are safe? "Yes, because I've used them and I haven't got pregnant" is the response.

Because she's using condoms, Estelle believes she's taking care and being responsible. She is, as far as she has the information to be. But health professionals say that young people are routinely let down by the education system, their teachers and wider society when it comes to easy access to good-quality contraceptive advice. It means that myths abound, and teenagers fall back on the limited and highly subjective experience of their peer group.

There are numerous problems facing teenagers when they find themselves needing contraceptive advice, not the least of which, says Hollie Kluczewski, national co-ordinator for Sexpression, is that nobody talks about young people having sex in a positive way.

"It's all very mechanical. 'Please pee in a pot for a chlamydia test and here's a condom,'" she says. "If you always talk about sex as a frightening thing – 'sex kills' for instance – then you feel bad about having it, and then you're not going to access services."

Sexpression is a nationwide organisation of mostly medical students, supported by consultants in sexual health to offer peer support to young people on any sexual health or relationship-related topic. The students volunteer in schools, community centres and youth groups. Kluczewski says that creating an atmosphere where having sex is seen as normal, healthy and positive does not mean "plugging sex", but being open and honest about the questions that arise.

Some schools, she laughs, are "awesomely keen" to invite Sexpression students; in certain cases this is because they're on the ball, but in others it's because teachers are distinctly reluctant to take on the task of teaching anything other than the basic reproductive facts. Teachers' wariness around practical help for sexually active pupils is failing young people, says Gillian, 20, who relied on condoms for two years "because I didn't really know much about other forms of contraception".

In school, she explains: "It wasn't really properly done – I found some of the teachers struggled to talk about it, and they shouldn't".

After a pregnancy scare, Gillian is now on the injection, which is repeated every three months. But she says she needed better information earlier, and that school would have been the natural place to get it. Her view is backed by a Studentbeans.com survey, which showed 45% of students saying they wished they'd had better sex education at school.

"We do know if you repeat the message, it's more effective," says Stephanie Mallas, executive director of quality and safeguarding at Brook, the sexual health charity for young people.

When a teenager does make an approach to sexual health services, she says they are often given "a lot of information that's quite difficult to comprehend". At a GP's surgery, there will be a time pressure due to appointment slots. At Brook or a community clinic the doctor will have longer, but it's vital to understand, she continues, that in order to talk through all the issues a young person may need to discuss before they are willing to try or adjust a contraceptive method, even an extended 20-minute appointment may not be enough.

"There's been a lot of – well, not pressure, exactly [but encouragement] – to use implants, but there are side effects," she points out. "You need time to talk those through. Spotting, for instance, isn't nice, especially for a young person just getting used to periods."

If there's been a problem with one method, and a young woman has had to return to the clinic, "there may well be real reluctance to consider a different measure. You'll get 'oh well, I'm not bothered any more,'" Mallas says. Without time and a genuine willingness to take their problem seriously, she points out, it might be months or years before that young person feels they want to make another approach.

Young people may also not entirely trust that health professionals will give them all the information, negative as well as positive, about a particular method they're being advised to try. They know, says Dr Caroline Cooper, a specialist in sexual and reproductive health "that we want them to have long-acting contraception and worry that they won't be able to stop it if they want it taken out. They might have a friend who's been and the doctor has said, well, just give it a bit longer to settle down, when really they wanted it out. And it only takes one person in a friendship group to say they've not had a good experience [to put others off.]"

Health professionals need to accept their priorities may not be the same as those of teenagers, and allow young people to make a choice they're comfortable with, say Mallas and Cooper.

"Young women worry about the hormones and particularly about weight gain," says Cooper. "That's at the bottom of doctors' list of worries but often near the top of theirs. With the long-acting methods, the implant and the injection, and the IUD, they worry about the procedure."

There is no method of contraception that is 100% safe and 100% side-effect free, but particularly for young people who may feel less comfortable about negotiating the nuts and bolts of more intrusive contraceptive measures, Mallas wonders if more might be done to think creatively about what works psychologically, as well as physically for a teenager.

"One of the newest methods is the contraceptive ring, and put frankly, it involves rummaging around," she says. "Part of me thinks that if this is the most modern form of contraception, what are they thinking?"

• Some names have been changed

• This article was amended on 27 November 2012 to correct the name of Dr Caroline Cooper, who was referred to as Dr Catherine Cooper. The picture was also changed because the original showed a method of contraception (the Norplant implant) no longer available in the UK.