Forge and diff. mods compability

[minecraftruplayer]

So, hello.
I wanted to install a couple of mods, like industrial and other.
So I alread installed AE2, BC2, IC2 and a couple of addons.
Also I want to install GraviSuite for IC2 and Flanl's mod.
I want to install it on the version 1.12.2 that I play right now.
The problem is the GS and Flans requires latest version of Forge, then other mods.
For example, Flans for MC 1.12.2 requires version 2611 of Forge, but I got newest.
So that means I cant use these mods together. When I launch MC at Forge 2611, it says I need to uninstall AE2 and another 2 mods.
So what I must do, to play with all the mods I want?
I saw somebody playing with these mods on 1.7.2, but my version is 1.12.2.
Sorry for bad english