I have never thought of myself as agoraphobic at all until recently, but now I'm beginning to think of that as my main problem. I have a few questions, though. I know that I can't get an online diagnosis, but if I explain my situation hopefully someone will be able to tell whether this sounds like it.

I started getting panic attacks when I was about fourteen. They got worse and worse when I was out. Gradually, it became harder for me to venture outside and now that I'm seventeen I realised I can't do it. It happened so gradually that I didn't even notice I had such a big problem.

I haven't spent a night away from home for years. Severe homesickness, panic, physical illness etc.
I haven't been able to even think of a holiday abroad. The phrase 'never in a million years' comes to mind.
Sometimes I can walk down the street without feeling scared, other times I can't.
The problem isn't with going TO places, it's leaving home, the only 'safe' place, that's the problem.
I feel like a dog tied to a lampost. I can move so far, but I'm always dragged back.
I feel constrained and...whatever the opposite of free is.
I can't get a bus into the nearest town by myself.
I can't go anywhere at all - not even around my village - without my mum. That's the most embarrassing problem. I don't have a problem being left at home while she's at work, but if I'm going out, she needs to be there.
Sometimes I manage to go out with people and without my mum, but I don't feel as safe.
I don't always get full-blown panic attacks: usually when I'm out I get one symptom at a time. Overwhelming nausea, a headache, choking feeling, dizziness. The symptom doesn't go away until I get back home.
When I do go somewhere, the 'difficulty level' is judged by low long it'll take me to get back home if I'm ill.
The main thing that stops me from going out is the thought 'what if I feel ill?' I think it's all health anxiety.
Sometimes when I'm out, I feel exposed. Like the world is massive and frightening. The buildings seem to tower over me and I feel dizzy, as though I'm going to faint. I feel the need to go to a small, quiet place and lie down.
It can feel as though I'm standing on water, not solid ground. Like I want to cling to something in case I 'fall off the edge of the world'. Dramatic, but it describes the feeling.

Sorry for the length of this! Does it sound like agoraphobia? If so, what can I do about it?