Hi, firstly i think it could be ok to be touching your stash. Depending on how u are freezing it the milk can only be kept abt 3-6 months but different websites say differently. On the other hand, the context of our bm will change as the baby grows older, so it is also good to be constantly using some of ur stash so that your stash's "meant for" age is not too diff from your baby.
There could be a drop in supply because u are more tired now looking after baby on your own so its pretty normal. It could also be because baby is a small baby still so not very good at totally emptying the boobs so --- not so empty so not so much replenished supply.
I suggest that after you latch baby, after 30 mins, u pump again. Take a variety and more of your milk boosters. Drink more water. Rest well - its hard but he husband of someone to help u at night too.
I definitely had LO waking up a lot at night - sometimes its just like that. - could be nightmare, sleep regression, hungry, uncomfortable, looking for soother (want to suck nipple. - in this case u can give pacifier). Baby is very capable and smart, if they hungry, they will really suck and drink, but sometimes they are just suckling and not drinking