I used to have exactly this problem. I'd be good all day, right through dinner, but then the evening snacks would torpedo my efforts every time.
What worked for me was a popcorn snack halfway between dinnertime and bedtime, plus one or two delicious herbal teas. I stress "delicious" because not all teas taste all that great, and I wanted something to look forward to. I generally don't sweeten my tea, but if you feel the need, then use a Stevia-based sweetener, which is low glycemic index.
For the popcorn, get yourself a microwave popper or an air-popper. I typically use a few sprays of Olivio spray (olive oil based butter substitute - the good fat), plus some popcorn salt. Never heard of popcorn salt? It's extra fine and works better for popcorn. Occasionally I'll make a savory popcorn with fresh chopped and lightly toasted thyme and rosemary, and recently I found an all-natural cheese flavoring that tastes very good. It may become my new favorite.
I time my popcorn snack for 8:30. If I get hungry after dinner, I can summon enough will power to wait till 8:30, and after my snack (including some hot tea), if I get really hungry, I just go to bed.
Breakfast is easy. Lunch is easy. A healthy apple or two is enough to get you to dinner, and a frozen dinner is a no-brainer way to get safely to 8:30. Popcorn and hot tea will add the cornerstone you've been looking for! Good luck!! /Jim F