Late... And now confused

This is my first month really trying. I got off bc in November. My cycles have always been slightly irregular. This month just baffles me. During what we thought was my fertile window... Well you know what happened. Now I'm late. Just 4 days but I'm going on day 36. Last month was 33. The month before that was 29. I have had cramps and tenderness in my breasts and have been weirdly tired for about 2 weeks but no spike in temps or spotting.