I went to see the specialist, as well as the lip tie she has a mild tongue tie so she doesn't sustain a suck. He seems to think the tongue movement is more of a problem than the lip. He won't snip either because she CAN suck properly, she just gets tired/lazy.
He said to run your finger around the inside if LO's lips before feeding to moisten and loosen them.
His nurse said if baby is struggling to bottle feed try a different brand- I use TT closer to nature and Avent because they encourage a wide latch, like breastfeeding, but the nurse assures me they're the worst 2 brands for babies with feeding problems! Any regular orthodontic teat would be better.