Is breastfeeding to sleep very bad?

[YellowSquirrel]

My baby is 3 months old. She fights all sleep. Either I breastfeed to sleep then carefully transfer to cot. Or I have to rock and shh pat a crying baby for up to an hour before every map (which only lasts 45 mins-arghh).
Easy option is feed to sleep. But everyone keeps saying this is a bad habit and should be stopping whilst she is still wee.

What age do babies self settle - should she be doing it at 3 months?

We started off by rocking and shh patting and then progressed to standing still shh patting then onto in cot shh patting and then just patting and then putting in wide awake. Moved forward a phase every few days.