Breastfeeding - use or store dilemma

My 3 month old is now sleeping about 7-9 hours a night (knock on wood it stays that way) but sometimes she would randomly wake up in d middle of the night and I would have to feed her but for the nights she does sleep the whole 7-9 hours, my boobs would be engorged and leaking so I wait until she wakes up. My dilemma is what should I do? If I pump at, say 3am and store it in my freezer, what if she wakes up at 4am? I know if I boob her after pumping she won’t get enough but it also doesn’t give me enough time to warm up the milk if I take it back from the freezer.

A little history - My milk didn’t come in until 8 days PP so I struggled with breastfeeding and continued giving formula and breast milk until my LO was 1 and a half month old. My lactation consultant said I had enough milk to put her strictly on breast milk BUT I might have expanded her stomach with all the formula I’ve been giving her. When I pumped, I was only able to get 1 oz per boob although the lactation consultant said she is drinking almost 2 oz per boob when breast fed.

My LO cries all the time when I unlatch her. I know sometimes her cries is because she’s comfortable on my boob but she also cries all the time even though she’s clean and had enough sleep. She’s not colicky. So it’s always in the back of my head that she’s not getting enough milk. Should I start giving formula again to top up?