Bad latch problem with breastfeeding?

My son is 9 months old and he still nurses every 2-5 hours. I've been noticing when he nurses that his mouth isn't in the correct "latch" form. I've had to adjust him to where his bottom lip would stick out in a pout. His upper lip won't pucker as it should in a correct latch and I hear a sqeaky, sucking sound (kind of like the sound you make when you kiss) when he nurses sometimes. I have tried to encourage him to open his mouth wider, but can't seem to get his upper lip to cooperate. He does have very small lips so I don't know if that has to do with anything. I noticed this beginning back when he was 6 months but it's started getting really noticeable within the last month. HELP!