OP from reading your post, I wasn't too sure whether you are looking for someone to support you to carry on bf or tell you that it's ok to stop... Firstly congratulations on managing to bf for 7.5 months despite all the problems you and your baby have had to overcome.
Regarding your breasts not feeling 'full' anymore, that does happen and it's normal. Whilst in the early months breasts feel full and heavy when feeds are due and then really soft straight after feeds, this isn't always the case later on - the fluctuation in the feel of the breasts calms right down.
Some women also find that at some point, months in, they just don't leak anymore. It doesn't mean that milk supply is dwindling at all.
This happened to me around 6-7 months and because my boobs never seemed to feel like they were 'full' anymore and I stopped leaking, I was convinced my milk was drying up. It wasn't, it was just a natural change and progression (and quite a welcome one really, not to wake up in the morning feeling ready to explode!. I ditched those breast pads without a backwards glance as well :) )
If one day in, you are already having big regrets about stopping bf and if your ds is not as content on ff as you envisaged, then why not consider continuing bf for one more week to give yourself time to decide whether it's what you really want? It's something that only you can decide when the time is right.
I second thisisyesterdays comment that if your ds suffers from a dairy intolerance, then ordinary formula (which is based on cows milk) is not the way to go, sorry if you already know this.
Maybe mixed feeding using an appropriate formula is an option for you in the medium term? You can then decide when to completely stop bf on your own terms when you feel ready to do so. Good luck in whatever you choose