"I have bent it back straight anyway". The difference between "actually aligned" and "looks straight" is tiny. I'd never try to align a derailleur hanger by sight, unless it was just a quick fix to finish the ride. The Park Tool align tool works great.
What are your shifting symptoms? Noise or chain pops in certain gears? Slow or difficult to shift to a larger cog? Won't easily drop down to a smaller cog?
Does it shift to the largest cog easily? And down to the smallest?
For shifting problems, I put the bike on the repair stand (or you could hang it by the saddle nose, I suppose). I shift to 2 or 3 smaller cogs, then shift back to the target cog.
Now I turn the crank very slowly (like 1 link per second) and watch the chain as each link gets near the cassette. Is it catching on the next largest cog? I can see the chain plate get pushed a little, then pop back in line. Or is it touching the next smallest cog? I'll do a few wheel revolutions to see what's going on.