I feel I am not progressing.
This is such a common feeling. Here are some reasons.
Not enough practice. Easy answer play more.
Ineffective practice. Not working through problem areas in detail. Lack of focus, ie practicing too many things at once. Playing pieces that are too hard.
Expecting too much. Unrealistic timeline. It can take years to master things.
Self-criticism. A little is helpful. Too much will mean every note will sound wrong. Play don't criticise. Adapt the here and now.
The plateau. You have reached a certain level and it seems hard to get any higher. Think sideways. Play pieces at a similar level but a different style. Swap speed metal for funk. Blues for Motown.
The quest for speed. This can be so hard. No matter how much effort you put in you are not the worlds fastest. We all have are own speed limiter. A combination of fast twitch muscles(lack of) and different levels of neural processing may be the biological reason. The good news is with practice you will get faster. Two contradictory approaches to combine. 1.Build up speed slowly with a metronome. 2. Play as fast as you can even with errors.