I looked and what you have is absolutely perfect.
I operate a Yahoo group for and have dealt with the aftermath on these kind of procedures when things go wrong.
Surgical Enlargment:
At this time the method being used is the implantation of testicular overlays. These have had a less than sparkeling track record. If the implant shifts and or is impacted it may cut off all blood circulation to the testicle and this can of course damage or destroy the testicle or testicles involved.
There has been a very high percentage of men who have also developed infections with the overlays and I have personally dealt with two men on my boards over the years that had testicular damage reducing sperm counts and hormone production after the damage was repaired.
Scrotum Filling with Saline:
This takes a real expert and is not to be taken likely. Those who do it seem to love it, but, it has many problems. In a few states possession of the gear required to accomplish this is illegal with penalties and other problems without a medical Rx in your possession.
Improper needle placement and the act itself can cause infection and or nerve damage. Some years ago I tried this and I must admit the sensation was really interesting, but the hassles and risks are not worth it. "It ain't THAT good!"
Drug Therapy:
This is very complex and these days even if you have a problem in all honesty getting help for it is going to be a total crap shoot. Most MD's will not even consider looking at your testicles regarding anything cosmetic especially on size related issues. If you decide to approach an MD, you need to discuss size in very definite ways. There interest will be peaked if you use the right words. Those words are "Shrink" "atrophy" "smaller than they were", "lack of sex drive" "difficulty with erections" and the like. IF you are lucky enough to get their attention with that they might run a few very cursory and unproductive hormone panels and then come back with: "You're over minimum hormone limits there is nothing we can do."
In truth if everything functions just dandy, your efforts at trying to increase their size could have the effect of increasing their size but at the same time actually reducing their function.
Unless something is really rediculous and you're dealing with a couple of peanuts (and there are a few out there that are) be wise, leave well enough alone.
Good Luck. . .