Your main complaints about your drug experience seem to be (a) feeling unusual, (b) having some difficulty managing your attention, (c) feeling excessively fidgety, (d) louder tinnitus, and (e) sleep difficulty. As someone who has experimented with psychoactive drugs a fair amount, including modafinil, my impression is that (a) and (b) are pretty common with psychoactive drugs and are almost always transient and harmless (unless you're driving a car, biking, operating heavy machinery, etc.). ((c) is less common but definitely present with some, e.g. coffee. (d) and (e) are probably good reasons to stop using a particular drug.) In fact, I've gotten to the point where I consider feeling unusual and having my attention work differently to be fun, interesting experiences to observe and learn from.

So my thought is that before trying modafinil, maybe people should experiment with small doses of strongly psychoactive drugs that don't have a 12-hour half life, perhaps in a safe & supervised environment, to learn that altered mental states aren't scary and can be pretty useful for certain tasks--they're like distinct mental gears you can enter using cheap, reliable external aids.

(For example, drink half a cup of coffee, then a full cup of coffee, then two cups of coffee on separate days to know what it's like to be highly stimulated, and a cup of beer, two cups of beer, and four cups of beer on separate days to know what it's like to be highly disinhibited. Kratom is another highly useful but little known legal psychoactive; for example, this successful blogger primarily credits kratom with his success at building his online empire, and I'm not surprised at all given my kratom experiences... any resistance I have to doing tasks seems to just melt away on kratom.)

(Disclaimer: I'm a foolish young person and maybe you should ignore everything I'm saying. Also if you really did experience stimulant induced mania you should probably follow the instructions on the label.)