hi, i am about 12 dpo my husband and i are ttc, i have always had semi regular periods, between 28 and 32 days. i have not been on birth control for almost 2 years although we only recently srated trying to get pregnant, i started very light bleeding the day before yesterday. it was pink and brown blood and since yesterday afternoon the bleeding is only spotting, i have done a hpt but it was negative, could i still be pregnant could this have been implantaion bleeding, or was that my period do you think? why would my period change? i also noticed that after sex the bleeding seemed a tiny bit heavier