I’m so bad at mechanics… any advice on how to improve?

I’m D1 in 1s and I am literally so bad at controlling my car. I’ve lurked in both this sub and RL School for a long time and I’ve been putting in tons of hours to improve but I’m really struggling with getting better mechanically. More specifically I am struggling with increasing my consistency on mechanics that I already know how to perform (shooting, dribbling, all sorts of aerials) but also I have been struggling to learn higher level mechanics like airdribbling, double touches and flip resets that are becoming more and more prevalent it seems . Admittedly I haven’t put anywhere near the same amount of time into these kinds of mechs as I have the more basic ones so I’m not surprised that I can’t do them.

Overall I’m honestly inclined to believe I may just be bad at using a controller. I have 7k hours and I don't really have the level of skill you would associate with that number of hours. Whilst browsing the sub I’ve found that deliberate practice is consistently mentioned to be a key driver of people’s improvements as such I have been using this as a framework for what my training should be for the last 3.5 years ( ~4500 hours) but as I’ve only gone from P3 to D1 and rarely D2 in that time I’m not sure it really is working. It’s gotten to the point where I am becoming convinced that I am the problem. 

Please help me, I still love this game and I am willing to put lots of effort into improving but I’m struggling to find a good place to put that effort.

(Also just realised that if I don’t mention game sense someone will mention it in the comments telling me that I should just focus on that instead, I understand gamesense is extremely important for ranking up and I’m doing replay reviews most days along with watching high level players play and analysing their decisions, to be honest I have been more successful at improving this than I have at mechanics)