latch and grunting

Hayden
I don't think my little one is getting a good latch. I don't think my nipples extend far enough into her mouth. I have a nipple shield that I use sometimes but it seems like that thing is huge! 
Any suggestions? Should I just go to pumping? I'm going back to work in 2 weeks and I really don't want to give formula. 
Also, she grunts and pulls off my breasts numerous times during a feeding, but especially in the beginning. And omg every morning she grunts and groans so loudly while still "sleeping" like she's trying to push out some poo....she toots some but she'll end up making herself vomit/spit up when grunting.