Thank you for replying!
I do wear makeup but I can't get it to cover up my birthmark completely. And it doesn't look very natural on me. So when I wear less makeup so my face would look more "natural" my BM shows through. But when I get most of the BM covered I look like I am wearing a lot of makeup and then people stare at my makeup.
By the way, some companies have policies now that you can only wear light makeup. But I am not going to do that because its not going to cover my birthmark well enough.
I have tried looking for a makeup artist who specializing in camouflaging redness so he or she could show me how to cover up my BM but I couldn't find one near where I live.