I'm in the same exact boat. About 3 years, high handicap. Similar distances too.
I've been really frustrated with instructors. Several hundred dollars paid and no real help. Okay, I'll give 1 guy some credit for improving my putting. But my swing has no consistency whatsoever. In fact, as I've improved my knowledge of the mechanics of the swing, its clear I've been given poor advice on numerous occasions (not that I'm the only one who's received bad advice).
I've decided that I can't rely on feel alone to figure out this golf swing. I'm taking video of my swing now. Its incredible how you can think you are doing one thing but in reality you are awkward as hell. I've observed several problems with my rhythm I can work on as well as stance, head, arm and wrist positions. Honestly some of these problems are fundamental enough they should have been pointed out to me by one of these pros I was paying. I tried out some changes last week with the driver and felt a difference in power and even a greater % of straight shots. I'll likely shoot some more video this week. I don't know if I'm qualified to recommend video yet as I'm still waiting for the benefits, but it's nice to have a new tool to try. I'm a visual person, so having a picture to look at helps me get a sense of what to do to fix it.