Might be pregnant. Again. please help!

It's silly I know. My period just ended on 10/15. I am on the pill, which I take 99% perfect. I use condoms every time. I have had bad headaches which have been making me nauseous, but I do not know if it from work or the weather, the headaches. Headache, nausea, and slight bloating are my only symptoms. I took a pregnancy test 10/18 which was negative. The day in question about becoming pregnant was 10/2. The only reason I think this is because I cannot remember if I touched precum and then the outside of the condom. I know precum has a small chance of getting someone pregnant, but he had ejaculated previously without urinating to "clean the path". I hope this makes sense. I have no other symptoms. I was nauseous while on the placebo pills, but felt better for two days once starting the new pack, and now feel bad again. Please help!!