no prob; just back on the boards after a 5 year hiatus...
Just feel around from your hip bone and keep the injection site fairly high and to the outside and you should get into muscle with what you have; although if you can get 1.5" I'd go for those; you can also push in some (so your cheek is pushed in a bit) to make sure you get well into the muscle.
But really you just have to judge for yourself, a 1 inch pin looks fairly long the first time you're about to jab yourself with it, lol, if you think that will still be in fat in the glutes, stick with quad or delt shots with the pins you have.
good luck