Good for you for reaching out for help, and for showing enough maturity to say that you know you are young. I assume you've come to Mamapedia because you aren't sure who you can talk to in your family or real life. You might be surprised that a parent can be more understanding than you imagine. But without knowing your situation, I can't be sure that's the direction you should go.a
You used condoms, which was a good start. Your boyfriend "checked the condoms" - but what does that mean? Before, or after? It's impossible to check for microscopic holes/defects anyway, but there are other things that can go wrong. And (I know this sounds dumb), has he ever been instructed on the proper way to use them to prevent accidents? I used to be a birth control instructor, and we did teach this to people!
As a minor, you have some rights, but not as many as if you were 18. To start, call Planned Parenthood's 800 number and explain that you need some advice. They will not reveal your information to anyone. If there's a clinic near you, they will let you know. They will also refer you to a local clinic that isn't necessarily under the PP name but which does similar work. You can ask for a sliding scale fee.
If you need to see your doctor (even your pediatrician - yes, they deal with kids up to college age), call and see if you can be seen without parental involvement. Probably not - at least not if you want to pay for this using your insurance. So do, please, consider talking to a parent or guardian. They may not explode or rant! You did show a level of responsibility by using condoms, and you didn't just jump into bed with someone - you've been dating for 2 years.
It's really too late to talk about how you "are too young" or "need to focus on your education." You've had sex, and so it's a done deal until you get through this situation.
There are plenty of reasons why a period can be missed - stress, adolescent hormones, even another condition, and certainly a change in medication. So you can certainly call your doctor and say that your period is late and you wonder if the medication can have an effect on that. And pregnancy tests are not always accurate, and sometimes there's just not enough hormone produced by an early pregnancy to make the test come out reliably. You can wait, or you can get a blood test, or you can have a clinic/doctor do it with your first urine of the morning.
If you can't talk to a parent, is there anyone else you can consult? Please don't call all your friends - you don't need everyone involved here. Try the school nurse, your doctor's info line, or (as I said above) Planned Parenthood. I recommend that you ONLY go to/talk to a clinic recommend by Planned Parenthood. There are plenty of organizations with similar names (like "Problem Pregnancy" and so on) which are NOT reliable, don't have medical personnel, and have a major political agenda that does not include giving your accurate info. You don't need value judgments or misleading info - you need facts.
For now, postpone having more sex. Just get your body straightened out before you resume. If you do decide to continue having sex with your boyfriend, please get a really good education on birth control methods and ways to increase the effectiveness of condoms. For right now, you have to assume both sides of the coin: you might be pregnant and need to take care of yourself, and you might not be and need to not get pregnant for real in the interim. I hope that makes sense.
Good luck.