Is there a NirSoft style global hot-key utility finder ? If so, that would tell you at a glance if you have any clashes.
So why not test your idea with Ctr-Shf-1 and 2 and 3, something like that. Make sure it works. Then your issue is simply a keyboard reading issue, can you hit a key twice for keyboard input, which you can bring up on the Autohotkey forums as well as here. Make sure you only have one variable at issue, reading a double key. (If you really want to go that way.)