Your email makes a teacher proud. It's amazing to me to think back to you less than a year and a half ago at the Merlefest jam camp. You couldn't keep time on your breaks, clutched regularly and were understandably frustrated. I remember how determined you were, though, and knowing you had served in the Marines, strongly suspected you would win the battle.
You're very much on the right path, and your having organized a jam shows the kind of proactivity that is typical of those who see the quickest results.
Re the “choking in a jam” problem, I suggest you:
1. Practice going from backup on a song into the solo, **while vividly imagining you are at a high level jam, and THIS is the time that counts.** If you imagine vividly enough, you'll give yourself an adrenaline jolt. Also imagine being stared at by the best/grumpiest picker in the jam, just as you're starting your break, and let that distraction try to derail you. Keep doing that exercise backup/break/backup/break until the break becomes "bulletproof". Close your eyes and see if you can play it. Spell your name while playing it, and see if muscle memory and what brainpower you have left can keep your playing on track. If you pick a song that's in both the "most vulnerable to clutching" AND "most likely-to-be-played" categories, you'll soon enough have a chance to prove to yourself at a jam that you can learn how to not choke under pressure.
2. If you have the Intermediate Bluegrass Jam Session DVD, put it on, and try to stay with it (two solos per song) right through the whole video. The speeds are typically over 100 bpm, so will challenge you. If that becomes "too easy", time to graduate to the Music Minus One Banjo, first the slowed-down CD (mostly 100-120bpm). Once you can handle that one, switch to the not-slowed CD!
Or... put on any good bluegrass record, through a slow-down program or CD player, and adjust the speed, first to a pretty unchallenging speed, then raise the speed gradually till you start stumbling. Come back to that speed as often as you can (add in the "vividly imagine being under pressure" thing), and the results should come. Be sure to use the Loop Exercise method when you discover repeated trouble spots.
If you are not too familiar with the Loop Exercise method, there's an article about it on DrBanjo.com under the Doc's Prescriptions. That is the central element of practicing for fast progress in my teaching. If you're able to make it to the Intermediate camp, you'll see it at work throughout. Everyone will figure out what practice loops they need to work on, and that will put everyone on the fast track.
Keith, I couldn't be more pleased to hear how it's going with your progress. Especially considering where you were at, early last year! If the Keith of then could see the Keith of now, I bet he wouldn't even believe it. Congrats, and have fun on the journey!