Am I over thinking?

I had been on birth control since I was 14 for PCOS. I am 30 now and stopped taking birth control last month mid cycle because I had not been remembering to take it and we are going to start trying to get pregnant. I did not get any withdrawal bleeding when I stopped. My husband and I had unprotected sex 2 weeks ago. 2 days ago I started having bad nausea especially to certain smells and having food cravings. Today I had a small amount of pink blood when I wiped and minor cramping. Then it stopped. I took a pregnancy test yesterday and it was negative. Is my body ramping up for my period or was this possible implantation bleeding? Is it common to get nausea when stopping birth control? How long until I would get a positive test after implantation? I am most likely just way overthinking things but I would like another opinion. Thanks in advance.