Brown Discharge, Bad Cramps. Trying To Conceive. Off Birth Control. Help?

I have not had regular periods for the past 5 years since I went off birth control after getting married. I am sexually active and we want to get pregnant. No luck with over 4 years trying. I usually get pretty normal period about every 2 or 3 months. My last one was around Decmber 22nd lasting about 5 days average flow, using tampons and pads. On this past Friday I had a cramp went to the bathroom and saw little blood when I wiped, assuming that I was starting my period I put on a tampon, left it in for about 6 hours only to pull it out (very painfully) to notice there was little to no blood on it kind of brownish. On Saturday I only bled enough to see a hint of pink when I wiped and had a few bad cramps , then Sunday we even had sex and it was like I was not even on my period. Today Monday I had a really bad cramp went to the bathroom around 2pm and had some spotting. I put in a softcup around 2:30 and left it in until 9pm and when I took it out it only had a tiny amount of clear and brown liquid. Could I be pregnant, or is this somthing else. I had blood work done last year to make sure I was okay due to not getting prego for 4+year and irregular periods and nothing came back unusual.