Fussy and small feed at bedtime

My daughter is almost 6 months old and her sleep still hasn’t really improved after the 4 month sleep regression. She feeds every 2 hours through the night and I think one of the problems may be that for the last breastfeed of the night before bed, she seems really fussy on the breast. She kind of pulls off crying but wants back on straight away so keeps going on / off. She never seems to feed very long or take much for this feed either. When she was sleeping 8 hour blocks she would have a long, calm feed before bed.

Any ideas on why this could be?