Jeez, it's threads like these that make me so pleased that I'm not (knowingly) surrounded by MN'rs in RL!!!!!
OP, firstly, YANBU. Your DH agreed to look after your DD so he should see that through.
A relaxing day out searching for dresses is not going to be just that with a, oooh, dare I say it, bored 10mo. I have a DS like your DD (and seem to have cultivated another one too now
}, and I did actually take him to one shop, with one friend, looking for a BM dress when he was 10mo. I hoped he'd stay in his pram and eat. Oh no. He ate, then squirmed and screamed until I let him out, then proceeded to spend the next however long trying to topple the full-length mirrors over
. Luckily the shop assistants were lovely (it was a very cool retro shop, not a typical snooty wedding shop) and helped us out. But it was not fun or relaxing for any of us, and one shop was more than enough.
Just because some of you have no choice but to take your DC's everywhere doesn't mean that the OP has too. I don;t see why it;s such a ridiculous notion that a 10mo may NOT be happy sat in a pram all day when mum tried on dresses. All babies are different, some are more relaxed and easy going than others (I'll be ordering one of those next time!)
His brother is 6mo, and I have actually been stopped in the shopping centre before by someone "suggesting" he needed to be taken home and fed (I'd just finished feeding him actually) as he was causing such a racket.
Unfortunately you made the mistake of drip-feeding a little bit which is a hienous mistake on here. That is not cool I'm afraid.
But, I do get the issue with your MIL. Although my MIL does not have any health issues ( which of course does not preclude you looking after a child, but unrealistic expectations of yourself maybe an issue), she does have a far more relaxed attitude to parenting than me. I struggle with this, as yes my DH and his siblings all survived their childhood, but they actually do all have various scars from incidents they had at home when they were small! Not that she could have avoided all of these but some of the things she thinks its alright for children to do, I don't really agree with!
HOWEVER she does look after my DS's because it's good for them and it's good for her (and so far they have all survived
)