During my early pg, I had a nagging ache on my side. It wasn't intense but it was a nagging dull ache. RE said it was probably the corpus luteum.
Good luck.. I hope everything works out.
I really am hoping it turns out ok for you. I've had cysts rupture without any bleeding but everyone's different so it could be.
I hate the waiting game also, sorry you are having to go through this...
Was the u/s a transvag?