Hi Everglades,
It sounds to me that first and foremost you need to get help with these long standing issues that are keeping you so anxious. Can your doctor refer you to counselling? No one should be alone with these feelings everglades and you need and deserve some support so that you feel more confident about work rather than just struggling through it, which is exhausting for you. If your doc won't refer you, try looking at
www.bacp.co.uk to find a counsellor. Good luck,
Loopy Loo