Hi, I Usually Have A Cycle Of 40 Or So

Hi, I usually have a cycle of 40 or so days. I've been having sex every other day since cd23. At cd 29 I thought I had gotten my period, however it was so light I didn't even need a pad. Barely a couple days later it's as if I never got any period, but my uterus feels full, like I guess if you have held in pee, but I'm not. I've also been more tired, but I know these are all pms symptoms. I've never had a light period like this. So it's like I'm on cd32 or just had a ridiculously light period and am on cd3.. Just not sure