All right it's a stupid question with a lot of details you probably don't need to know but I have to ask. My boyfriend and I tried to have but I couldn't fit it in. We tried once and stopped literally after 3-5 seconds and then tried again and the same thing happened. So my question is could I get pregnant from just trying? I'm on birth control and I haven't missed a day and take it pretty much at the same time everyday (the latest is an hour after I need to take it).

No question is stupid. Any time a penis gets that close to a vagina, and you have to take into consideration pre-ejaculate which there would have to be if he was READY, and given that any form of contraception is not l00% safe, the answer is yes, there is a possibility. You will have to wait until your next period to know. Sorry for the bad news. I am being realistic.

There are just as many of those eager little devils, spermatzoa in pre-ejaculate and these forerunners do the job just as effectively.

Possible, but not likely, especially since you have been consistent with your birth control. See what happens when you expect your next period.

The main thrust, no pun intended, of your question has been answer though I want to address a comment you made. You could fit his penis in your vagina? Were you properly lubricated? Many women of all ages don't produce enough lubrication so it is hard and painful to insert the penis. Keep in mind that your sexual organs are meant to be able to pass a baby though them, so unless he's about the size of a baby there should be no problem inserting his penis. What might also cause a problem, and you never mentioned it, is if your hymen is still intact.

Use lube and communication.

I've had 2 periods & taken 2 pregnancy test at what would be 6 almost 7 weeks pregnant (both negative) but I still feel kind of sick like nauseous and have constipation and keep burping and peeing. Could I be pregnant?

Chances are still heavily in the NO region.

I would look to your doctor to figure out your gastrointestional issues that are completely unrelated to your current reproductive health. That would be more concerning to be honest.