Record Yourself - Self-Assessment
"If you think you got it, record yourself and listen back to see if you 'really' got it" said Rod Piazza in a conversation regarding preparation for the performance of a song.
It's difficult to listen to yourself closely enough while playing to make an accurate assessment of your performance. Make use of the easy tool of recording (most of us have phones or computers that have recording software and microphones built in) for self-assessment.
Recording is the process students use for submitting material to me for review. When students listen back to their first recorded take, they commonly hear areas that they're not happy with and work on those areas for a bit and then rerecord. By the time I receive their final recording they've commonly recorded their piece four to five times. When I receive their recording, most of the basic rhythm and technique errors are fixed... I can focus on areas that need improvement that they're incapable of hearing (thus why you're on this site, to have the ears of an expert to help you).
Make use of this self-assessment process, it's what will help lead you to the mastery of this instrument.