I understand what you mean. It is difficult to remove any protective wall you have, whether it be physical like make up or something emotional like suppressing your feelings.
When I was in high school, I suffered from depression because I believed I was inadequate and a failure. I wanted to be like the other kids who were experiencing life and being happy with who they were, but I wasn’t and I knew that. I knew I was different and it definitely brought my self-esteem down. I felt like I was in a class system with everyone else on top and me on the bottom. So I suppressed any emotion that was negative in order to create this facade of a perpetually happy guy, so that no one would see the depressed kid underneath. But it didn’t make me feel like them, it made me feel very alone.
When I finally discarded this facade and accepted who I was, I began to feel so much better about myself than when I was faking it.
If you spend a day, an afternoon, or even a minute without make up on, I believe that no one would think any less of you. In my opinion, a woman’s beauty is determined by how she feels about herself, not by how she looks.
I can tell that you are a strong person because you were able to reach out on this forum to anyone who’s been through what you have experienced and because you have been struggling with this for a long time and haven’t given up. You are still searching for solutions. Not a lot of people have the willpower to do that. You can definitely beat this fear.

It doesn’t have to be today, tomorrow, or even within the month, but I hope that sometime in the near future, you can look at your reflection with no make up on and simply say, “I love you for who you are”.