Hey, I suffered from this when I was 14 (dont want to bum you out), but this came up suddenly, because I could ejaculate fully with my girlfriend. I had fixed the problem after about 2 months though as we just tried new things, get my drift.
I think you should practice your partner to arouse you. I think you're not aroused when you have an intercourse with your partner that's why only few drops came out of you.
if you are a guy you might have retrograde ejaculation
no theres nothing wrong with you. you just havent been aroused enough to.