do ff babies sleep better than bf babies???

Lisa
Hi
My baby girl is 6 months & 1 week old. She used to sleep great 7/8 hrs straight , up for 1 feed then back down for another 3+ hrs.
For the past 6 weeks it's as though she's a new born again, waking up 3-4 times each night wanting to feed.
I am weaning her now & each day she's having more & more food. & since 4 weeks old she's had 4oz formula before bed (sometimes she won't even have any cos she's full)
Just wondering if any of you have switched from bf for ff & your baby has slept better?????
I thought this was just a growth spurt but to last 6 weeks is very long??
Any advice?
Baby isn't constipated or anything, poos 2x daily since having more food. 
P.s. Still feeding 8-12 x per day also
Thanks