First: You aren't a terrible chess player. I think you know that. Your tactical scores show you have at least decent skills to be able to calculate.
What you may be is a very under confident chess player. Some people, for whatever reason, are very poor at evaluating where they really stand in terms of ability. You may be one of those people. Or maybe you are one of those people who need to be told they are doing OK on a frequent basis.
Second, I totally agree with Deirdre that you need to be patient. There are no quick answers in chess. Chess is a brutal mistress and takes a stupid amount of study to get good at it. If you really think there is a magic answer that is going to turn you from OK chess player to good/great chess player in a month or two, you are sadly mistaken. No such program exists. No such program can exist. If that is what you are looking for, you are playing the wrong game.
Occasionally, a player who has been stuck at a rating for a long time will suddenly blossom and increase greatly in strength (a couple hundred points) in a short time period. But when that happens, it is because of a great deal of study that suddenly integrates and they get it. Silman relates how that happened to him. And it is possible it will never happen. Chess is a cruel mistress.
Of course sometimes kids increase in strength quite rapidly. But if you look at what they are doing, that is no accident. They basically immerse themselves in chess.
All we can do as chess players is try to create a sane plan for improvement including both study and play of the right types and then do that plan relentlessly, trusting that it will eventually pay off.
I have been working my plan since around April. It has been paying off in the sense I can tell I am much stronger now than I was back then. How much a difference it will eventually make I don't know. And anybody that says they know is basically a snake-oil salesman.
The same is true for you. There are things you can do to maximize your chances. You need to do those things. How high it can take you and how long that will take nobody can really say with any certainty. But there are things you can certainly do in your plan that maximize or minimize your chances for success.
If the above isn't an acceptable answer, then you may want to strongly reconsider your commitment to this game.
I have no skills no visualization ability no ability to calculate variations or god forbid I should even know how to spell 'positional' skills.
Nevertheless, I want to be great at chess. What's the key to this?