If you have vanilla TF2 you should probably get some improved hitsounds and damage indicators
I use PVHUD which makes damage indicators larger and brighter and also displays your last done damage above your health. It is a "pro hud" however, and while it makes health and ammo larger it also turns all charge bars other than medigun into a very simplictic, bright bar without indicator so you should try out if it gets confusing for you. I think you can also download the damage indicators without the HUD but you'd have to dig around for that
Here's a preview of it, but it doesn't show the charge bar sadly. Oh, and don't worry, the awful looking floating spy arm has nothing to do with the HUD, that's the user's viewmodel which is something else entirely
Also try dingaling for a better hitsound. You could go for something silly until the joke tires out, and after that I'd suggest the good ol' Quake Arena 3 hitsound which is clear, simple and easy on the ears even when using the flamethrower