Harriet please stand up to her.
Please develp a bored tone of voice and use it on her. Say things like.
Not his again mum, I'm not 15!
I'm not clumsey at all, whatever makes you think that....
Don't accuse her of going senile or anything, just make it clear her views are shite and you are on to her and utterly bored by her.
EVERY comment she makes retaliate.
"only just revoering from the last time of holding a baby. "
No mu, wrong again, I am looking forward to holding the newest and NICEST member of the family.
Just work out in advance what shit she will come out with and hvae a reply ready. Say it how you like but I;d go for bored "Really mum you do talk shit" sort of voice.
I thikn it is good your dh wants to support you but please do not ever get into the situation where you cannot go anywhere without him. You need to be able to stand up for yourself.
And sometimes you need to say it like it is... NO, mum, I am not leaving because I am throwing a strop. I;m fed up with your rude manner and so I am going home, where people will speak to me politely.
If you want to be really brave ring her up tomorrow and say, "Mum, I just wanted you to know how inappropriate your comments were yesterday, I had come to see my new nephew and not you and you spoiled my time there with your silly comments about me and how you don't seem to think much of my abilities."
She will bristle and maybe be rude or she will apologize. You want the apology because you want to be able to say next time, privately, mum remember when we spoke on the phone about how your rudeness to me was not appropriate and you apologized? Well you are doing it again."
Do it now, please before you have your own kids, so that she never gets to talk down to you in front of them.
If you are kind you will call her and give her a heads up, you won;t take it anymore and will call her out on it. If she pretends not to know just read back the comments you wrote here and say that she may not realise she is doing it so she is going to have to work at not doing it.
Or ignore my advice, but whatever you do, do not doubt yourself, you will be a fabulous mother!