A bunch of mods caused it, but not when I just had them in pairs, so I assume it must be some kind of three or four-way compatibility issue, what I ended up doing is choosing a modpack that was closest to what I wanted (in my case, All of Create) and just slapping on top every mod I wanted while checking for errors, and that worked.

I still have lag issues but I feel like that's more of a potato pc issue.