I am 18 and my boyfriend is 19. We have been together for almost 2 years and have been active for about 1 year. He is the only person I've had sex with before. I feel like I have a difficult time orgasming. In one position, he stands on the floor next to the bed and I lay on the bed on my back with my feet on his shoulders. I have never orgasmed this way but feel like I get very close. My body tightens and I need to hold on to something and my breathing quickens, but then I feel like I'm going to pee (even after emptying my bladder before sex) so I stop him. In another position, me sitting on top with him also sitting up, I get a whole different kind of amazing feeling but do not feel like I'm going to pee. This is the only way I've really ever gotten like a satisfactory relief, but even finding that specific spot is so difficult that it does not happen every time we have sex. I feel so bad because my boyfriend gets so frustrated and feels like it's his fault Im not "finishing." So here are my questions: in the first mentioned position, am I actually about to orgasm or is there a chance I am actually about to pee? Is their a position that will have similar results as the 2nd position mentioned?

Most or at least a majority of women never have a orgasm while having actual intercourse but only do in fore or after play. So the fact you do sometimes means it is working.
Most likely orgasm,

My girlfriend describes an orgasm as "feeling the urge to pee" so I would say this is normal. You should do some research on your "g-spot" or positions that stimulate your g-spot.

I know most don't like when I bring this up but have you ever given yourself one?

No one knows you like you do. If you're open about it, I suggest giving yourself one. This will let you know what "it" feels like and then you can transfer that over into communication with your boyfriend. What he's doing right that feels like it and what he's not.

One thing to keep in mind is that some woman do not. Do not let this affect your relationship. It is not his fault no more than it is yours. Its just something that happens.

Good Luck!