Help?

So my boyfriend and I had unprotected sex. Long story short he came inside me but we were in between paychecks and didn't have the funds to by morning after pill in time. It's now three weeks later I'm a week. I've take 4 pregnancy test, 3 negative and 1 positive but I also don't really believe the negative tests. And I have a hunch. I haven't been feeling the same. Maybe I'm crazy?