Don't get too down about your extension problems. I have now torn my ACL 3 times in the same knee (i'm 22 yrs old), and am a medical device engineer so I have a bit of experience in this area. I wouldn't get too concerned, and as Im sure you've heard, everyone heals at different rates. I would just keep working at and go at whatever pace your body will allow.

It is much better to just go with it and take your time than to rush back. I tore my ACL/Cartilage for the 2nd time during my last day of PT for the first tear, thanks to a therapist who allowed/encouraged me go much faster than the prescribed time frame for rehab. I had significant problems after the 2nd time with regaining flexibility, but one week out of the blue it seemed to jump quite a bit and recovered faster from their on out.

So, just keep on goin with PT, and do what ya gotta do. Eventually, you'll begin to make bigger gains and be back good to go sooner than you would think.

(As far as the splint, I have not had any specific experience with that) Hope this helped.