Gagging when latching

My babe is almost 9 weeks and has recently started to gag when I first try to latch her and won’t latch especially in the middle of the night. Any ideas? I’ve seen 6 different lactation specialists who all sat latch is good ( I don’t agree) as there is clicking while she swallows and they all have said no lip tie or tongue tie even though her top lip doesn’t flare out. Anyways any reason she just randomly is having struggles? She use to sleep 5 hour stretches at night up until now and can’t go more than 3 hours. My supply seems fine and has plenty of wet/dirty diapers.