Can't get pregnant!

Jhawan • 20 Gemini. in a relationship. Mommy of one 💕
I don't think I can get pregnant and it bothers me! Me and my SO never used a condom and he sometimes even finishes in me, I sometimes even miss my period but when I take a test it's always NEGATIVE! My period is now 9 days late I just tested and it came back negative. Any suggestion? Have this ever happened to any one else! Help please!