I have only noticed hiccups twice now (i am 30 weeks). But I think I only noticed them because I had my hand on my belly, or I just happen to be looking.
They are very light (compared to kicked) and I can see my belly move every second or so.
Your baby is probably hiccuping, but maybe at times where you are busy and don't notice, or they are too light.
Good luck !
(sorry I can't help with the pelvic pain, I haven't had that)