Maybe I can help... I've had a denial and successfully appealed it.
I also have a close friend who was also denied ~3 years ago. He never filed an appeal, never did anything. Then, just recently, he tried to purchase another firearm, and was approved after a 3 day wait. So, judging by this, just because you have previously had a denial, that doensn't mean they'll automatically deny you later on. Food for thought... they'll have a record regardless... whether you pass or fail. If it's a denial they'll know in Virginia, and the gun store will have your 4473 if you pass.
My suggestion is to go buy a Yugo SKS or something for like 120 bucks. It's a good rifle even if you don't get approved.
Most importantly... read the law. If the law says involuntarily, and you signed a form saying you volunteered for treatment, then you are fine. Read the law a few times, read the disqualifying criteria and get all the documentation you can possibly get... be it from your dad, your local pd, or the clinic. Every bit helps. The drones at NICS denied me for something very different, but I knew I was right, I already had all my court documentation attesting to that fact... and 5 months later, I was ok lol. They make a lot of mistakes.
Just get your paperwork in order first, if you can. My record was changed in the FBI system as a result of the paperwork that I had. They'll change it for you, but not unless you have documentation... there is a limit to how much work they'll actually do... you may have to get the agency that added it to the index to clear it up for you...
Don't worry about it. Try to get something cheap, that's my opinion. If what you said here is the truth, you're fine. Just get all the applicable paperwork you can NOW... it gets harder to find later on and who knows when some turd in congress is going to disqualify people who are committed voluntarily as well. Of course, running some kind of local check may be an option, but I'm not sure mental health treatment even shows up. I wouldn't worry so much about if I would fail or not... while you're worrying, most likely for naught, you can't enjoy this hobby. Something like 700,000 denials were issued in the first couple years of the NICS... I doubt they're banging down all those doors...