Plonky you're one of those people who can just cook, lovely things, without effort aren't you?! I used to be. Now I cook scrambled eggs. Very good scrambled eggs I'll have you know, but even I'm getting sick of the monotony.
As for the girdle, DH approves. He has after much coaching learnt to approve of whatever I do. He doesn't often understand but he knows he has to approve 
Pud Teeth cleaning is a v quick flick top and bottom here as any more bores her. If it's quick she thinks it's funny. Your method sounds just fine to me.
Car seats we've got the Besafe Izi combi here, and it's massive. I am actually selling my car because it won't fit! It's also a bit of a fiddle being rear facing you have less room to fiddle about, and fiddle about as we all know is something that goes hand in hand with getting a resisting toddler into any form of seat. That said it is very safe, which is why we got it. I can live with the inconvenience if toddleworse is more likely to come out of a bad situation intact.
Feeding: we mix it about here. The tiddler likes her food soft, but will take lumps if it is all lumpy, rather than the occasional unexpected lump in an another wise mashed meal. I feed her the main part with a spoon and give her bits of finger food on the side to eat/play with/throw on the floor and basically do with as she pleases. She enjoys meals now, zero stress, and that matters more to me than her understanding the correct use of a fork and appreciating broccoli.
Sitting - no idea, but instinct tells me he'll get it eventually. There are very few 18 year olds stuck forever in a standing position. Well one assumes so anyway.
Milk is morning, bed time, and with snacks but not meals here. To be honest toddleworse dictates what milk she wants herself and I just go with the flow. I haven't got her to take it from a cup yet which the health visitor assures me is terrible parenting. So I don't tell her any more
. Again, I'd rather do things a bit more slowly without stressing dd over it.
As for us, well toddleworse is so well I have completely stopped stressing about her heart, and my lunch out yesterday was the best. You know sometimes you find a friend who just 'gets you' warts and all. My friend is one of those. Found her next door 8 years ago, and hope to still know her when I'm 90. Because I will still be here when I'm 90. Obviously!