latch and shape of nipple after nursing

Soon to be Mrs.Williams

I want to know what my nipple should look like after nursing. He seems to latch right away but when he's done my nipple looks round at the very base but looks flat towards the tip. Sometimes I get a pinched feeling when I nurse more on one side than the other. I have kinda flat nipples and larger areola so it's hard to get a lot of the areola in his mouth. Also it seems like once he starts more of my nipple starts slipping in. is this normal?

momtoRaegan041008

The LC told me it should be round.  Mine however are pressed together and flattened when she is done nursing.  It was very painful for the first week, but has finally started to not hurt so bad.  My daughter is constantly slipping off the nipple.  I have one flat nipple ane one not.  I notice this more on the flat nipple.  I also have trouble getting the whole areola in her mouth.  I just figured she had a really tiny mouth.