can i ask why you are already on a 4 hr schedule for feeds - is it because of the spitting up??
if you switch back to a 3 - 3.5 hr feed schedule you will get 1 extra bottle into her - and she might just continue to take 4 oz per feed = 4 oz or more extra
so you woudl feed 7, 10:30, 2pm, 5:00, 7:00 (last 2 are cluster feeds) - you can offer bottle then bath then bottle then bed, then try the DF closer to 11 and see if that makes a difference. if she wakes up earlier just start at that time and you can space them better (ie 6:30, 10, 1:30, 4:30, catnap, 7pm + DF)
Olivia had slept through from 10 1/2 weeks until 12 weeks, then had 3 mo growth spurt. it took until 4 months for her to sleep through again but then she never looked back so be patient with your lo. nigt wakings for food are extremely common until 6 months and even after 6 mo are normal (just less common). i woudl not offer any solids until 6 mo - if she won't take more than 4 oz bottle i am betting she will not jump onto the solids and it is better for her to wait. Olivia only occassionally finishes a bottle so apart from offering her a full bottle at DF (we used to offer 6-7oz because she only took 3-5) we just continue to offer usual amount for feeds and hope for the best (she takes between 4-8 oz per feed and it varies every day, she has always been this way)
you are doing all the right things and if she slept through before i imagine she is just getting back on track from 3 mo GS (i assume that already happened, because otherwise this sounds like a GS to me). if she wakes at different time in the night and takes 3-4 oz (since her "usual" feeds are 4 oz) than i woudl assume it is hunger.