Q&A: I just recently got off the Depo shot. Could I be pregnant?

I just recently got off the depo shot. I was on it for 8 months. I have been on it prior for two years then when i got off of it it took no time for my periods to get back to normal. My husband and I are trying to concieve. Last month in january was the first month I wasnt on the depo. I had an irregular period, but it lasted for 5 days. This month I thought that I might be pregnant , because we had intercourse everday. I took a blood test on the 21st. it came back negative but we had intercourse on the 18th and it had been 4 days prior that we had it. My period this month I have only had spotting of old blood that only lasted for an hour and wasnt enough for a tampon, could I be pregnant, My breast are real tender still. I am confused, plus there is a discharge that is real thick. How long do I need to wait to take a home pregnancy test?