As for the 'overcompensating' statement. Be kind to yourself. Don't try so hard. You already are a singer. Your mission is to find a way of singing that is easy, but strong. It really must come from a CALM place. You do your best singing in the shower and in privacy. Learn to cultivate that energy and presence while you are in the midst of people. Most of the time it isn't singer issues people have, it is intimacy issues. This isn't always the case, but I imagine it happens a lot. Learn to go deep inside yourself and calm yourself so that your singing flows out of your breath and not from the things you think you can do with your brain. If your body is tense from stress or nerves...you will disconnect from your body and your breath. Go inside. Do meditation. Really learn to sing as if no one is watching. Once you have that tamed then you can see if it helps with technical areas. I imagine you will find that your high notes are easier and you like it more. Calm. Take time to get a good inhale and good exhale. Phrase by phrase. Slow it all down for awhile and you will see what I mean by 'go inside'.
I hope this helps! I wish you all kinds of good luck and love for yourself to pursue the craft of singing.
Keep me posted!