I used to always have a problem with my pinky the first time I played (played for several years then put it up for several years and just got back into it the latter part of last year) and I would always just compensate with my 3rd finger. Part of my problem is the length of my pinky. I do not have short fingers but my pinkys are rather short for some reason. I physically can NOT hit a note on the E string with my 4rth finger..just can't and thats on a Jneck even...
Anyway, I was reading around here one day about the use of the 4th finger. I even commented on one thread that I just work around it and thats that. Well some poster commented that he didn't feel a player was a true player if they didnt use their 4th finger. I didn't agree with them buuuuut it did get some determination under my butt... I play a lot of original pieces and I came up with this one piece where I HAD to use my 4th finger or it just wasnt going to work....so I did...took several days and after I got good with it I went to the standard Jazz riff (E3,A2,A3,A5,D2 and reverse back to the E3, repeat then A3,D2,D3,D5,G2 reverse back to the A3, repeat then go back down etc etc) To play that before I always had to use my 3rd finger for the A5/D5. After practicing the one riff with my pinky, that finger did the A5/D5 just fine. I have really built the use of it it and I can feel a difference in it even.
Practice that riff or come up with something where you have to use the pinky and just keep practicing. I still can not hit a note on the E with my pinky well at all but I can sometimes and I know its because I have finally been building that finger up. I have also built up the reach of that finger so on the occasions when I can use my pinky for the E string its easier now down the neck..or that up the neck? I can never keep that straight.. I can hit E string notes easier with my pinky now on frets closer to the nut (but still can't use it farther up/down the neck -- toward the body.. *sigh* whatever LOL).
Keep practicing, it can be done.