First off, don't be so damn hard on yourself. I'm sure there are many people that have been palpating people for years - they're usually the ones that grab a girl's ass in a crowded room - yet they don't count....
OPP palpation and diagnosis is a learned skill - gets better with practice. Actually, the "learned skill" is the ability to be CONFIDENT in what you feel. Remember, neurophys? We all can differentiate so many microns of stimulus (unless your neuronally damaged - w/c is a whole other story).
At NSUCOM, as a MS2, I've had the opportunity to work both in the OPP clinic and in a free clinic sponsored by the UAAO (OPP Club). I've also been fortunate enough to be described as "good with my hands" and at OMT. I still, with patients, use a sheet of paper to describe sacral torsions, my hands to describe innominate challenges and vertebral somatic dysfunctions, and I still place the head in the position that it is "living" before I reverse planes for HLVA or ME.
Professionally speaking, I get to chance to explain to the patient what is "off" and how we're going to fix it. Personally, I talking myself through the Dx and Tx - keeping everything straight in my own head.
Practice. If your an M1, grab a classmate and say "hey, lemme try something - it will only take a minute." Most people are okay with this, as they'll probably need a body to practice on in the future and you DID say only a minute
If you are a MS2, practice on the underclasspeople. That is there acknowledged yet never agreed upon role: test dummies for the sophomores
If you build it, they will come (movie quote, anyone?). More applicable, if you practice it, your belief in what you're feeling will come.
And, if you get the chance, goto Convocation. 100% hand-on learning - plus skiing this year!
Good luck!
-A