More general:
* Self-critical
* Self-deprecating
* Hypercritical
* Overly demanding
* Unkind to yourself
* Putting too much pressure on yourself
* Beating yourself up
* Dwelling on mistakes
Focusing on the negative emotions:
* Self-punishing
* Doubting yourself
* Lacking self-compassion
* Feeling inadequate
* Having low self-esteem
More positive alternatives:
* Setting unrealistic expectations
* Needing to be more forgiving
* Learning to be kinder to yourself
* Practicing self-acceptance
* Focusing on self-love
The best word or phrase depends on the context and the specific message you want to convey.