Before you go for a new coach, or no coach, at least approach them with your concerns or complaints as a courtesy. I may have missed that above, if so, apologies.
At least that way, they will either say something, nothing, or they have feedback if you leave.
If you've won something, must be doing alright by me. Best indicator of performance is performance itself. I find around here the 4/5 stuff has a lot of "career 4's" and "triathlete 4/5's" who could move to 3 and won't. So often the 4/5 races finish with faster speeds than the 3's do. But, being a cluster FK of zero brains or strategy among folks like me who aren't too bright.
I say that to say if I had to spend money on a coach for 4/5 and didn't plan on moving up to 3 within X years.........I'd only do so to manage strategy and skills. I wouldn't do it for fitness. Just me.