period or implantation bleeding??

Deana
Ok here it goes.... my periods have been pretty crazy lately from 32 days to 41. Well my periods are always really heavy and painful. On cd 30 I have some spotting, it lasted about 5 days it was soooo much lighter then my period. I took a test a day after the spotting stopped and got a BFN. Today is cd 43 I have had slight cramping and sex feels different for me. I'm having a hard time reaching climax sorry for tmi. I usually never struggle with that lol 
Maybe it's all in my head but I feel pregnant, when I got the bfn my head told me no that's not right. I have been way moody lately my boyfriend keeps mentioning my attitude and usually I'm not moody until I'm on my period or at least the week before. I'm not sure what's going on but any insight at all would be great.