What does it mean if I only had a 2 day period after getting off depo ( it has been a month now )

I had unprotected sex while I was on depo , I just got off it about 2 months ago . I had a period but it only lasted for 2 days . it has been a month since I had a period now . I have been feeling alot of symptoms such as , nausea , peeing more , headache's , irregular bowl movements , diarehha , chills . ect ect . My doctor thinks I could be pregnant but I know thats impossible because I took over 5 pregnancy tests and they all came in negative , and my doctor took a blood test , but that was around when I had my last period . Thoughts?