I'll try to help and address some of the STA-21 stuff.
1) You don't have time to apply this year, the cut off is 01 JUL.
2) It is an EXTREMELY competitive program. It took the 21 enlisted-to-commissoned programs the Navy had and melded them into one. There's still LDO and CWO, but you have to be in Khakis (or an E6 testing for Chief) before those are an option.
3) You have to have 6 interviews with an LT (O3) or above. 3 that are in your CoC and 3 that are in the URL that you're trying to get into.
4) You'll be grossly under-qualified (rank, time in service, overall knowledge, evals, etc) compared to the men and women with whom you're applying.
The list goes on, but here is their official
website. It has all the information you'll need.
As I suggested earlier, go to the fleet, get some experience and then make your decision accordingly. Everyone that I have spoken to has said that doing your X number of years in the fleet before going back will make you a better candidate if you choose to try it again.
Also, I would assume (because I don't know) that something anyone wanting to get (back) into an SOF pipeline would have is the ability to think for themselves and make their own decisions. You've said twice now that you want someone to tell you what to do and how to do it. Do your own research and figure out what it is YOU want to do. Navy EOD techs are shit hot and I refuse to think they got there by someone holding their hand the entire way. That Crab is not easy to earn. EOD has a prep course here at Great Mistakes just like BUD/S does. I'm starting to ramble.
Anyhow, I bet your "knee pain" was ITB related. Guess what the most common over usage injury is in SPECWAR pipelines... Gotta pre-hab and foam roll everything, my friend.
I hope this helps some.