Thank you all for the input! It's really reassuring to know that I'm not the only one who sneaks around my own house

and seems like a Jekyll/Hyde character around different groups of people!
I just discovered a section in my CBT book that addresses social anxiety, so I think I'll try to use that to re-frame the problem - like your suggestion Daenerys - if they're talking to me regularly then they probably think I'm OK!
I had to do a presentation the other day for uni (it was worrying about it that prompted me to start this thread), but it went surprisingly well. I practiced it lots and noticed when I was getting flustered, so took a deep breath and didn't panic. It was probably one of the best presentations I've given in years!! So I wonder if it's something I can learn to live with.
If things do get worse I will go to my GP... I just feel like I have enough diagnoses already; I really don't want another label unless it guarantees a treatment that will help. But I know CBT is a good option for a lot of anxiety disorders so if I can work on that on my own first then it seems like a good option. And I'm already on an SSRI for depression at the same dose as is given for anxiety, and don't really want to take any other medications if I can help it!
To be honest I think all I was looking for was some reassurance that I wasn't being pathetic and that it CAN affect people in weird/specific ways. Thank you :)