Flat nipples

I have flat nipples... well more like nipple. My left side is flat. I cannot for the life of me keep it hard enough for my daughter to latch on ( I know they don't suck on the nipple but I can't trigger her suck reflex). I used a nipple shield earlier and she latched on but I hate using it because it's not natural and I don't want it to effect her suck on the other side ( right side is fairly good and she usually take it no problem). Shoukd I keep using the shield or are there any other suggestions to help with my nipple problem? I've had to pump after she does eat just so I have relief from being engorged. Oh and we've only been doing this for 5 days and I've never breastfed before. Thanks for your help ladies