Thank you all very much for being nice to me - your advice is all well-received and very helpful, and I'll take it all on board (including asking Muse to send me ideas for things to wear!).
I think my problem is that my weight now defines me: I think about it all the time, and to some extent project it onto what I assume others are thinking of me. A little while ago we were all having a good-natured moan about the women in our lives that we envy - the ones who get diffed easily, who are successful, etc. - and everyone who had that conversation ended on the trump card, "AND she's a size eight!". I know that, in our heart of hearts, this is how we judge other women (although truthfully, I don't), and it makes me feel panicked about meeting people. Because that's the yardstick for beauty and success: is she thinner than me. And 90% of the time, I will be heavier than you, and so the balance is always one of contempt or pity towards me, because whatever else I might have in my favour, I have committed the cardinal sin for a woman: I am overweight, and therefore I am worth less than you (the 'you' here is a general one: I'm not picking on anyone in particular!). Sure, I have a nice face. But so what? I'm fat. Maybe one day my novel will be published, but who cares? Everyone knows the only thing other women admire is how thin you are. I'll have a PhD by the summer hopefully, but fuck that, I'm wearing a size 16 cardigan.
Does that make any sort of sense?! I must sound quite, quite mad, and I promised to stop being insane and here I am carrying on. But I've heard the way people talk about weight, and what they value in women, and no-one ever says, "I'm so jealous of my SIL/colleague/best friend: she's the kindest person I ever knew/has the voice of an angel/was the youngest ever QC/won the headmistress of the year award". Nope, they say, "She's a size 8, the cow!".
I am using the BESH board as a sort of therapy tool, sorry. But I wanted to explain WHY this is making me so miserable. The fact that I am overweight makes me effectively worthless and contemptible, because over and over again women (including the BESHes!) have said "She's thin!" as, if it's the final arbiter or what's an achievement in a woman.