Great to hear you've started at such a young age!
DLD's
SRT Program is tremendous, check it if you haven't already. You mentioned about "lost exercises", I think many good exercises are easily found on the forum. Making an unique one is up to you!
Girth wise I'd say you're quite golden, at least considering your base. You can try to even it out to the tip if it is somewhat uneven with the Slow Squash Jelqs.
http://www.mattersofsize.com/forum/penis-enlargement-forum/12539-slow-squash-jelq-nothing-give-me-better-expansion.html
That's one exercise I highly recommend.
Then there are various other squeeze techniques, like DLD's toilet seat compression. For this exercise you just need a nice, flat area.
One related exercise in the clamping section "related" to this:
http://www.mattersofsize.com/forum/redzulu-s-penis-clamping-universe/51698-shane-diesel-and-shorty-mac-width-secret-exposed.html
Yes, more about the width, but I feel this could also help in evening out the girth on your whole unit.
I'd say to go with these for the moment. I'm personally in favor of clamping quite a lot for girth gains, but it's best make most of the gains with your hands first.
For clamping you can still get the SWM's clamp. http://www.mattersofsize.com/forum/redzulu-s-penis-clamping-universe/88967-hanger-penis-clamp-yep-still-available.html