late period ...odd symptoms.. odd cycles ..help

hi everyone... in January I was diagnosed with hypothyroidism and my thyroid is back normal with medication. since around January my cycles have been really off. I get a heavy period at my normal time for 5 days. about 10 days after it stopped I start again lighter for another 4 to 5 days. finally got into my doc. have to do blood work on day 3 of my cycle to check hormones ect... well my period is 3 days late and I habe been having pretty bad cramps for the past 4 to 5 days which makes me think I'm always about to start . yesterday I had brown spotting only when I wiped once.. since then .. nothing ... my doc didn't think I was ovulating due to me having 2 cycles a months.. what the heck is going on with me . I don't think I could be pregnant.... anyone ever gone through anything like this. thanks