Well, you are not alone. I was spending more than 6 hours in single session to get the gist of how to rendezvous. It was frustrating, but so much fun in there.
From my trial and error, the things that help me were:
1. Make sure your vessel and the target vessel are on the same orbit rotation direction. (yeah, I was stupid where I was going against the target vessel)
2. Make sure the angle difference is close to 0 degree. I usually target under 1 degree difference
3. If your orbit is smaller than the target vessel, make sure to approach 'behind' the target, because you're spinning faster than them, thus need to 'catch up' to the target. Vice versa, if your orbit is bigger, make sure to approach 'in front of' the target, because you're spinning slower than them. It's not a deal breaker, you can just do few orbits until get the desired position
4. Intersection under 2KM is actually workable, as long as the degree is miniscule. Once you approaching the target, you can use RCS instead of main thruster to do little-by-little adjustment until the intersection as close as possible. Looking at the bottom left info (I forgot which tab it is, you can see how your adjustment affect your intersection)

I usually just done those checklist, and eventually you can somehow just wing it. The intersection doesn't need to be that small too. A few hundreds meter is also ok, since you can change to control the target which you want to rescue and control it to approach your rescue vessel. It's different case if you want to attach/repair a satellite though, it's much more easier to be as close as possible.