6P, looking at your vids in slo-mo with QuickTime ...
Comparing your takeoff point to the thick white mark on the runway, I agree that your first vault was ~1-0 under, your second was ~0-6 under, and your 3 attempts at 14-0 were "about right" ... relatively.
But I think your target takeoff ... for where you're at in working on your free takeoff this season ... could still move out a couple inches ... and still not feel too far out to you. i.e. even your last 3 jumps were a bit under, IMO.
Your plant on your 2nd attempt at 14-0 was late, but I thought it was OK in your last attempt.
My theory on why you bailed on your first 14-0 attempt is that your step was "on", but that surprised you (you weren't ready for it), so the vault didn't feel quite right to you. Also keep in mind that when you're "on" or "out" you need to have a tighter body (top arm, shoulder, and torso) so that you EFFICIENTLY absorb some of the impact when the pole hits the box. That's kinda the difference between letting the bottom arm COLLAPSE versus driving the lead knee and stretching into the C that Altius and I were bantering about the past couple days (on the One-arm drill thread). On ALL your jumps, you're letting your bottom arm collapse, rather than driving into a good elastic stretch ... staying "tight". The further out your takeoff is, the tighter you need to be ... and the better "body posture" you need (search for "kirk feofanova" about this). (When you're under, this flaw isn't as apparent.)
I also noticed that you were dropping your lead knee in your 13-6 clearance, and in your last 14-0 attempt ... but not so much in your other vaults. I don't think you should intentionally drop your lead knee, because you're having trouble swinging/bringing it back up, so you probably lack the swing speed and/or gut strength to do this. Although I know your abs are strong, they're probably just not strong enough for this specific vault part. Work on those on the highbar and rings.

The main SYMPTOM that I see in all your vaults ... even your makes ... is that you flag out. Why? Because you're getting jerked off the ground ... not getting much of a downswing ... and digressing from there.
Even on your near-makes, you could have saved the vaults if only you shot straight up instead of out ... towards the bar. How do you fix that? Well, you're flagging out because you're losing your momentum into the pit. I know it sounds ironic, because you APPEAR to be blowing thru on your last 2 jumps, but actually, you're just flagging out. Had you shot UP instead of OUT, you wouldn't have hit the bar like you did. You would have hit it on your way down.
You know that I don't usually recommend that you fix an upper vault part until you've fixed all the lower vault parts. In this case, I still don't recommend doing anything to fix your flagging out problem. I'm just mentioning that as a key indicator (a SYMPTOM) of the problem.
I could just blurt out how to fix this, but I want you to do a little contemplation about it first. So you tell me ... how do you think you can fix your problem of always flagging out?
I'll give you my recommendations in a day or 2, but since you've made such a BIG STINK about not having a coach at nationals, I want you to DEAL WITH IT by becoming your own coach ... and you can't do that unless you become more retrospective. Not that you're not retrospective already ... I like the way you analyze your own vaults ... I just want you to do more of that ... now that I've given you a few pointers.
Also, I don't know what your coaching situation is for the outdoor season, but please remember that it's YOUR PV CAREER ... you have PRIMARY responsibility for your own success! No offense to your coach, but he's just your helper. YOU'RE in charge! Don't whine about not having a coach to catch your step or advise you between every jump. Just learn to become more independent and self-analytical. I KNOW you can!

Kirk