73 day cycle.. today I visit the doctor

Sophie • 29.. married.. longing for our family..
I'm on day 73! Never had such a long cycle before!! I'm in the bath it's 4:45am and I woke for the third day in a row! Today it was for stomach ache and it would appear I have trapped wind hence the bath 😩
This long cycle is annoying me!! I've taken 3 pregnancy tests all negative I just want to know why I'm having such a long cycle! I doubt I'm pregnant so ladies what else could it be??