I think you have a problem with the mechanics, namely that you want range. It's a weird concept for space battle for anything other than, say, lasers. As you know, deep space is very empty, so for all practical purposes there's nothing that stops something moving indefinitely. There's tiny, tiny amounts of hydrogen, but any drag that might produce is negligible for any non-universe spanning distances. Battles near astronomical objects like planets, stars, or black holes would influence range due to the effects of gravity or have terrain features that might prematurely stop projectiles, but other than that you should expect something you shoot to keep going until it hits something.

If you want to keep range, you should come up with a plausible reason for it. For example, you could say there's something like a space Geneva Convention that bans weapons that do not have internal explosives that automatically detonate, vaporizing the weapon, after a certain prescribed distance. You should then keep in mind the implications of your solution. One implication of my example would be that any explosive that could vaporize the weapon that contains it would also be powerful enough to be used offensively, which makes every weapon a bomb, really. Of course the implications of a solution don't have to be bad; again, regarding my examples it might be tactically interesting to consider every weapon a bomb, or it might be interesting to think about a military force that intentionally violates the convention.

Or you might do away with the concept of range altogether and replace it with something like propellant, or delta-V. Weapons would be differentiated by how much and perhaps even the capabilities of the propellant they carry. You might replace flak with something like swarms of small tactical nukes that carry a small amount of a powerful propellant, allowing it to make very quick course changes at short ranges to maximize its effectiveness as an anti-missile point defense weapon. Kinetic weapons would carry no propellant, and accordingly have no delta-V, and that's exactly why you like it; any space that would have been used to carry propellant is now filled with a dense mass of fuckyouranium, making a powerful unguided weapon. Missiles carry a lot of propellant, and can therefore make a lot of course corrections, meaning it can follow a maneuvering enemy.

This comes with its own implications, of course. It does somewhat preserve the idea of short, middle, and long-ranged weapons; nuke swarms are unguided after they spend their propellant, while kinetic weapons are unlikely to hit at distances far enough away for enemy ships to maneuver. That said, they would still effectively have unlimited range, which opens up tactical possibilities. A standard tactic might be to fire weapons in order to create area denial zones while also forcing your opponent to maneuver, to then fire the weapons you actually intend to hit your opponent with towards the areas your opponent is forced to maneuver into. Having delta-V be a central mechanic also makes it more important to determine the speed weapons are traveling at, because that is part of determining what kind of tactical maneuvers are possible in a given situation.

I would also switch the damage values of kinetic weapons and missiles. Without knowing the underlying economy of warfare here, it seems that in your current schema that missiles are king. If you shoot enough missiles you can overcome any point defense weapons, while if you stay far away enough you can maneuver away from kinetic weapons. Battle would basically be determined by who can shoot more missiles first. Switching up the damage values for missiles and kinetic weapons would change the game; there's more incentive to move in closer to actually use kinetic weapons effectively, while the damage they can do makes it more urgent to maneuver away from incoming kinetic weapons. This would, I think, make for a more tactically interesting scenario that values deft maneuvering and weapon use. There are other solutions, too; you could make it so that you have a very limited number of missiles, for example, such that you will be forced to use kinetic weapons, but that means most of the battle will be fought with only two weapon types instead of three.

It sounds like you're on a good track. If you think your mechanics through a little more, you could have something very cool.