I see medical translation because it deals with more technical stuff is much more difficult to translate than ordinary everyday language, your boss should know this. I really don't know what to suggest when it comes to your work problems, do the other translators get the same treatment as you? Just seen it's only you who does this technical stuff, could you not ask to translate some of the less technical stuff and another translator the more technical stuff? I'm trying to help but feel I'm rather out of my depth. It certainly looks like your boss is a bully the way she treats you.