At 7 months, her A time should be at least 3 hrs. This would explain the short naps you are getting and the all around fussiness during the day... she is undertired to start with, takes a short nap and feels refreshed, but really isn't. She then enters the land of being OT and quite often, this will cause bottle refusals... she can't bring herself to focus for the 10 mins she needs to because she is tired.
I would keep her up longer in the morning... do it slowly though so that she doesn't have a total melt down... 5 mins every couple of days unless she does seem happy being awake... you want to push that first awake time to 3 hours... this should lengthen her first nap and then allow her to happily be awake for a second stretch of 3 hrs (at least) then take another good nap... allowing you to get rid of the third nap - she should only be taking two at this age.
I would also consider changing to a fast flow teat... she could be frustrated by the time and work required to drink a bottle.