Help? (TMI.. Kind of)

Miranda • 22, Engaged, & Just found out I`m pregnant with our first little miracle. <3
Okay, so my fiancee and I had been trying for a while, but it became super stressful and we quit trying (Sept 2014) AF came October 27, last 8 or 9 days.. And was pretty normal while she was around. Well... November 27th came and went.. I tested on Nov 27th and it was negative.. So I figured it's come in a few days... Well.. December 4th came and went and I decided to test again on Dec 5th.. It was positive.. I've gotten blood work to confirm, & my first appointment is Dec 15. My problem / question is. I'm having some cramping, nothing severe, they get kinda strong for a second and then go away.. They aren't constant, and it doesn't happen all day or everyday. But I'm really starting to worry, even though they're more of a dull ache than a cramp... What could it be? I've had (small) bowel movements, nothing like normal so maybe a little constipation? I've had a miscarriage before so naturally, everything freaks me out.. Please help...