A sense of self should be flexible, and not get stuck on particulars, in order to be okay. This is based in the premise that people are inherently worthy, and self-worth or identity shouldn't be rigidly attached to things that come and go.
This article by Dr. Diana Hill talks about the difference between self as content, and self as context. In a context, you are sometimes this or that, depending on the situation. She mentions a runner who can't run anymore. If her identity is tied up in being a runner, who is she if she can't run anymore?
She does still exist. She is of course still "her." She isn't "a runner," she's a person who sometimes runs.
Depending on circumstances, you can change your mind, learn, grow, or be different, with more or less support, or opportunity.
A big part of mindful practice is noticing that you are a person doing and experiencing things, and also that you can observe yourself doing and experiencing things. This observer, removed from the doing and experiencing, but watching, is you.