How I stop this paranoia?

I’m 17 and me and my boyfriend have been in a very wonderful, healthy relationship for a good year now. I lost my virginity to him and he’s the only person I’ve ever had sex with. He’s also very careful using a condom as well as pulling out, but I still have these paranoid thoughts ever since the first time I’ve had sex.

Every time my period is on its way I get extremely scared. I can’t handle the paranoia I get, because it genuinely makes me think I’m pregnant. My period is also pretty inconsistent, I don’t know if it’s from the stress, but sometimes it’ll come 4 days early or 10 days late! I’m going through the same thing, and I’m expecting my period today. However, I took two of those pregnancy tests that claim to say they can detect HgC before you even start your period (up to 6 days) and they’ve gotten good reviews.

They both came up negative- I even used early morning pee.

Yet I’m still scared that I took the test too early. Is there anything I can do to help myself? So many other girls do riskier things and yet they never think the worse. Is a therapist a better option? I’m a very anxious person.

I’m also getting pretty thick white discharge and very mild cramps/back pains, they’re not as bad, but they’re almost like the ones I’d get on my period.