I'm concerned hat I may be pregnant and I don't want to be. Please help? :(

I am 15 and I'm worried that I might be pregnant, I didn't have sex but I gave my bf oral sex and swallowed then after about 10 mins he put his penis in me but took it out after, it's 5 days after that now and I have really bad back pains and I think i've missed my period, my boobs ache too. Also i'm weeing more often, I feel stupid for asking this but please help :(

You can chat/text/call a women's health professional for free at plannedparenthoodchat.org. They'd have better answers.

You said: "he put his penis in me"... Where? If it was back into your mouth, then you can't get pregnant from oral sex. If it was anywhere else, they may be close enough to get you in trouble if there was sperm present. (It only takes one.)

You need to make sure you understand birth control if you're going to be doing what you're doing. As Rob often says:

The web page below has nine links at the bottom. If you understand all of the information on those pages, you will clearly understand how it works and the risks of different behaviors.

Planned Parenthood:
http://www.plannedparenthood.org/info-for-teens/pregnancy/am-pregnant-33831.asp

get a test