I am so sorry you are feeling as you do. Please try not to beat yourself up about mistakes at work, everyone makes them and being stressed and beating yourself up can lead to "proving" yourself "right". It is much better if, when you feel scattered, you slow down. (say, at work could you go to the bathroom for two-four minutes and just do some deep breathing or use an earbud to listen to soft music?)
I am also sorry your mother is so focused on medication. It sounds as though you could really use someone to talk with who would listen and provide you with emotional support and help you develop the skills you need to be able to care for your mental and physical health. Do you have someone to talk with? And do try to take a bit of time each day to do something nice for yourself.
Is your husband supportive? It must be a difficult time for both of you. Is there anything you can do together (?happy family planning) to relieve some of the pressure?