14 month old begging for food at night

We have a 14 month old Parson Terrier mix. When she was a puppy we were feeding her Fromm Puppy, but she constantly had terrible gas and loose stool. When she turned a year old the vet recommended we switch her food to Hill's Prescription Diet Gastrointestinal Biome Digestive / Fiber Care. Luckily that has helped a lot with the problems she was having.

However in the past few weeks we've been having another issue. I normally feed her in the morning (9am) and the afternoon (1-2pm). In the last few weeks she has started aggressively begging for more food at night (between 7-9pm). Hitting her bowl, doing her terrier frustration growl noises etc. We've even tried feeding her more than the required amount (bag says 1 and 3/4 cups for a 20lb dog, I'm basically at 2 cups for a 19lb dog) at meal times with no success.

She looks lean and in good shape so I'm not necessarily opposed to feeding her more but the main issue is when we feed her at night, she has to get up to poop sometime between 12-3am. Our first dog never acted this way, I don't want her to go hungry obviously, but I also don't want to be overfeeding her and getting up in the middle of the night because of a behavioral issue.