I'm just betting you have a lovely smile that lights up a room. I'm just betting that your "aura", for want of a better word, is warm and welcoming and makes people feel cherished. And I'd also hazard a guess that you and your family were dressed sensibly for the weather, instead of skirts so short they might as well be belts, or trousers so tight they can't have been doing their lady bits any good at all; and tiny little kitten heels or the like...
I went through my schooldays having to put up with stupid comments like those from those girls you encountered - I found it interesting what a pp said about "rough areas" as that's exactly where I grew up, and basically, a lot of the people I went to school with, unfortunately, had been trained, more or less, to go for what they perceived as the weakest point. So for me, I was small, a bit overweight, couldn't run very fast, not fashionable, not interested in the slightest in fashion or pop music, very plain, very poor, and wore glasses. It's one of the reasons I ended up so sarcastic - I got to the stage where I'd get the insults in first before they could, and they got so scared I'd turn my tongue on them I got left alone some of the time. I also practised saying "Drop Dead and do the world a favour" in a tone that made it sound like I meant it on occasions....
The other people I encountered who made comments about how plain I was were (wait for it) a so-called "Christian" sect....(I wasn't a member, I was visiting a friend who'd been taken in by them after years of being a splendidly amusing lapsed Catholic. They were a lot more fun as a lapsed Catholic and thankfully are now a happily lapsed Catholic once again. This was one of many comments throughout the weekend that made me wonder why my friend couldn't see through them.)
I got those comments not because I wasn't attractive in my own way, as one early ex put it; I got picked on because I wasn't fashionable and didn't really care about having the best designer labels (partly as we couldn't afford them but partly as I just didn't care. I still don't understand why some parts of society fawn over "influencers" and celebrities. It's all made up, and it's starting to unravel, thank God). My mother used to tell me not to take it to heart, but of course I did: it took several burned bits of paper/paper flushed down the loo/plasticine effigies before I felt better. A friend of mine who was also small and plump used to take to writing things in the sand and jumping up and down on the words and chucking stones at it until she felt better; the tide used to come in and take the words away, and with it, quite a lot of her anger and upset.
And the amusing thing is, we've both aged far better than just about all of our contemporaries. (There's one exception, but I forgive her as she's a lovely person.)
Those girls should remember - their mirrors might tell them they're the height of what's fashionable and attractive now (though I bet they're not, in reality), but we all age. And some "pretty" people don't age all that well. I've worked with people who were told they were dazzlingly beautiful in their youth (apparently - they were blonde, anyway, and slim before they had kids) and oh boy, have they taken getting older hard. One of them told me "you get invisible to men as you get older". And it made me laugh out loud, since I spent most of my life being "invisible to men".
Besides which, illness, stress, life - all leave their mark one way or another. Being basically kind and thoughtful and looking after others and good at what you do will last far, far longer than being a painted stick insect.
And as for their behaviour with the dogs and not calling them off when they were obviously upsetting your little 'un - one day it might be their kid that's being traumatised. One day it might be them. And it's hardly unheard of for those kind of untrained dogs to turn on their owners. They sound like utter twits and you sound lovely, kind, sensitive, and a great mum and wife.
(Though if it won't go away, I would recommend writing it down on a bit of paper and either burning it in a mini-barbecue, ripping it up and chucking it down the loo, or writing it in the sand and jumping up and down on it if you're anywhere near a beach. They're all very therapeutic. Ahem.)