What I mean is that you do not need to let your perception of what other people think of you determine how you feel about yourself.
For sure, a genuine compliment from another person can make you feel better about yourself, but if you have low self-esteem, you might disbelieve the compliment or feel that you need to have compliments all the time to feel good about yourself. How you feel about yourself can become largely dependant upon what you think other's opinion of you is.
When you have high self-esteem, you accept and enjoy compliments, but can choose to disregard derogatory comments. That's not to say that you should just disregard any criticism of yourself because you think you are great and everyone else is wrong. That is arrogance. You can take on board criticism, evaluate whether or not it's valid and decide whether you can improve yourself in that area. But when someone is being nasty, for example, slagging you because you blush easily, you can decide that the opinion of that person is irrelevant.
I think it's also important that you do not go around being disparaging about other people. It's creates negative energy and does you little good. If you set yourself a moral standard of behaviour where you react to people in the way you would wish them to react to you, you can feel good about yourself for meeting your own standards.
If you read up about what SA is, why your blushing is happening, and begin to understand the mechanics of it all, that alone can help. If someone thinks you're a bit weird and avoids you because you blush a lot, it's because they're ignorant of your condition. It's your faulty thinking which is preventing your true personality to shine through. If you work on changing your automatic negative thinking and building your self-esteem, you will gradually find yourself able to be yourself again.