Looking at the save game ... well couple of things.
Neutering doesnt equal killing everything.
Probably would've needed to scout better and earlier.
I see a lot of planets that are dead without any reason whatsoever. 3 still have their K in them. If you wan't AI to not launch waves from there, kill gate, eyes, and any warp guardians. Not CMD.
Also you've got core world alerted permanently, that is bad.
Aip should still be at tolerable limits, and game might be salvageable (barely). You are too spread, need to consolidate defenses. First priority should be getting warpjammer on murdoch.Halt all current fort /golem constructions. After that, bait all the stuff waiting in ai coreworld and kill them. Build some defenses on murdoch (preferrably turrets, ffs 1 fort at some point ,probably not now). Then get kalxi , shuihahanhaoihnahnoa (those worlds, forgot exact names). Destroy all AI worlds between these worlds and your other worlds. Move all your forts and turrets to these 2, murdoch and wibiyaiyiay (your westernmost world). Remove forcefields in your deep worlds and move them to these worlds.
After that you can still take systems, golems ARS ,CSG, to prevent Deepstrike threat. I wouldn't take many though. And you can't keep them, mine them out of K , repair golem, leave.
AIP amount is doable for 7 difficulty, but you need to absolutely limit the amount of ingress points for AI. Warp gate raiding is completly useless at this kind of AIP.
If you want to start a new game, i would recommend X map. It suits this kind of playstyle pretty well.
Cough, wanderers opinions about ai are bit skewed towards playing extreme challenge games
edit: played the game a bit. Doable still but hard yeah. Not sure if reinforcement sare working as intended, that carrier spam seems rather extreme for default difficulty.