The thing with mental health stuff like anxiety, depression, OCD and all those kinds of things, is that they so often end up going together. If you think about it, they have to in a way. It's pretty hard to be so anxious you can't leave the house and not end up feeling depressed. Similarly, it's pretty hard to be depressed and not start feeling anxious about things that are difficult. And it's hard to have a severe phobia and not get really bad intrusive thoughts about it and resort to compulsions to reduce the anxiety. When I look back at the times my anxiety was worst, I think I probably
was depressed, and I started doing OCD behaviours as well, just because they all do go together. It wouldn't surprise me if you were depressed - if some kind of 'official' test showed that, because in a situation like yours it's difficult to be happy all the time. I think the important thing is not to treat them as different things - you don't 'now' have "anxiety AND depression", you just still have "really horrible mental stuff that makes you anxious and depressed". I know it doesn't seem that different but I think treating them as part of the same whole makes it easier to deal with - you don't have to try and treat them separately somehow, just try to treat the whole problem and they will all, eventually fall away. I promise.
I just have to say that I really relate to the feeling of being trapped and unable to get out of somewhere. That's pretty much my main sticking point too - I'm terrified of things like lifts, trains (and especially planes), as well as places where the 'trapped-ness' is more subtle and social, like school (like you said about it not being appropriate to leave when you're out with your friends).
But also I have to say that I think you need to think about those situations differently. Just imagine if you did leave soon after you'd arrived in town with your friends. What would actually happen? They might think it was a bit odd, but they'd probably be worried about you more than anything else. They'd just want to know you're OK. How much do they know about your anxiety and stuff? Maybe if you told them a bit about situations you struggle with they'd be able to support you a bit (if you haven't already that is). I normally find the best way to reassure myself is to tell myself that I really could leave, whenever I wanted, and
nothing would actually happen. People might think it was strange, they might be a bit disappointed that the day out had ended early or whatever, but apart from that - what would the consequences be? Nothing, no one would die, no one would hate you, nothing life-altering would happen. Maybe when you're going into one of those situations, you just need to give yourself a bit more perspective on whether you really care about 'socially acceptable' or not. In my opinion, when you're in the depths of something as horrible as you're going through, it's not worth trying to maintain social rules. You just need to start being selfish and doing things for yourself, because that's the only way you're going to cope better day-to-day.
OK, there's two things I have to disagree with here. The first is that they were a problem for your mum. It's not nice that she had trouble with them, but you really can't use that as a reason for
you not to try them. Everyone reacts differently, some work better than others and there are so many different types of antidepressant anyway, it's silly to base your opinion on them on one incident. It's fair enough to be reluctant to go on medication, because so was I. But there's really no harm in trying, because they can have a truly miraculous affect.
The second thing is that they don't solve the problem. That is true in one sense - they don't do anything about whatever the true underlying cause of the anxiety/depression is. But they shouldn't be viewed as a plaster which just covers it up - instead they're a plaster cast. They don't just mask the problem, they make it more possible for you body to solve the problem itself - or more accurately, your mind. They give you the boost you need to get back into ordinary life and figuring out, and sorting out, what it is that's causing the anxiety. They don't try to treat the cause, they just make it possible for YOU to treat the cause. Because really, you are the only person who
can do that - it's your problem, in a sense you're the only one who can ever do anything about it. Just like there's nothing doctors can do to physically fix a broken leg, all they can do is put you and your leg in a situation that makes the healing easier - keeping your weight off it, putting it in a cast so it heals straight, and so on. Any treatment you get for the anxiety is just helping you to deal with it, and antidepressants are just another tool you'll have in your arsenal to help you cope day-to-day so you can work on it properly. I urge you to at least consider them.