The hard number of the limit is 64 MB of script data. There is no simple way to measure it, so not a very useful limit to know.
You'll need to disable some mods, I recommend City Plans first, as they are high in script data, and see if you get past the spinning vault icon - which is the number one symptom to tell us your load order is over the limit.
Modding Bethesda games with more than a small handful of mods is not auto-pilot. If you want to run a bunch, it's going to take some tinkering. If that's not for you, then you might want to try something like Wabbajack.org. Those are mod packs you can download where someone else has already figured out all the technical stuff so you can just play.