@JoshuaD2002
If you are really concerned about your hearing at 8khz, then I'd recommend going to see an audiologist and get a proper test done.
If you had significant damage at 8khz, you'd probably notice it....
You can then compare that to the one you have done at the audiologist in February.
I've never been hit by a football in the head, but I've copped a fair bit of noise very close to my ears thanks to my children and my hearing hasn't changed in 2 years - and I'm 40. You are young and the healing power of your body much greater than mine.
I think you are fine.
I hope I'm not out of line, but you are showing signs of OCD. This can be hard to control without professional help. You are honestly wasting your youth on this obsession with your ears. IF you have lost some hearing (which I highly doubt), right now there is absolutely nothing you can do about it. That's the reality.
My recommendation is- get the hearing test at the audiologist and speak to your parents and GP about your obsessiveness over your ears.
I don't mean to be offensive, so please don't take it like that.... you are ruining your life with this obsession.