just came off birth control, could I be pregnant already??

So I had my period July 3-6, started a new pill pack the 6th but then stopped taking it the 13th. I got my period again July 17-21 after stopping the pill. Had sex 3 times during the green "fertile" days on my glow calender as well as other times before ovulating. Past few days I've been super nauseous, sore nipples, peeing more often and when I have to go I have to go really bad all of a sudden, sense of smell is stronger, and more sensitive during sex (in a good way). Could I be pregnant already?! Took a hpt a few days ago which was negative, but I know it's way too early to test, since my period isn't due until August 13th... any suggestions/comments? I've only been off the pill for three weeks.