I can certainly understand how the experiences with your mum must have really left their mark on you, it must have been really hard for you.
Just wondering if you've ever had the opportunity or whether it would be a possibility to talk to your mum about those times, your feelings and the feelings that followed?? Those sorts of things can all too easily be "swept under the carpet"/not talked about but obviously they don't just go away like that.
If it hasn't been/isn't a possibility though I'd definitely say talk to your psychiatrist about it though. For some, the more talking the "easier" it gets.
Have a think about what they/you can do to make the appointments easier as well? e.g. if they tend to not start till later than scheduled you could phone up from outside first to check on how they're running and make it for then, as you're not going to be wanting to sit around in there waiting (!), take something/anything with you to focus on while you wait, if you can schedule your appointments try for early morning (?) when the thought of going isn't going to be hanging on you during the day??.............And I would say try to distance yourself from what happened with your mum when you're going but I know that must be really hard, so maybe just something to work on if you can.
Got to sign off now but around tomorrow, so will reply then if you post.
Best wishes
Alison