Competitive tennis is very hard and never gets easier.
Tennis looks a lot easier from outside the court.
Losing is a big part of tennis. Even at the pro level, only one player goes home a winner on any given week. Expect a lot of losing.
If you have never played competitive tennis you really have no idea of what goes on on the court.
There will always be a crisis. Bad losses, loss of confidence, injuries, etc. are just around the corner. Be patient, they are part of the process.
If you find yourself constantly looking for different coaches the problem is probably not the coaching.
Even when you optimize everything , results cannot be controlled or guaranteed.
The journey should be fun for both, you and the player. If one of you is not having fun, there is a problem.
The player should be a lot more motivated than you. When this is not the case you are heading for disaster.
If you are getting frustrated imagine how your son or daughter feels.