I say you go with a fresh install to rule out you possibly messing up something (forgetting to delete a folder/file, overwriting the wrong file etc.)
Press the windows key + r (a little box of sorts should show up).
type "%appdata%"
open .minecraft and backup your saves folder (copy and paste it to your documents for example)
After you've backed up your saves folder delete your minecraft folder entirely
Open up Minecraft.exe, force update then retry installing the mods following the instructions to a T regardless of how tedious they seem. Also the backpack mod may be conflicting with these others mods you're trying to install. Anyhow, do a fresh install and reinstall the mods afterwards.
(I had the same issue until I did a fresh install and re-installed my mods)
Tell us what happens
