I haven't read all the replies, just OPs.
I think, and I'm saying this genuinely not to be cruel, that you sound quite insecure OP. You obviously have issues around the fact your partner had a life previously with his ex and child and that he isn't experiencing the same 'firsts' as you.
I really hate it when people say this but this was always the way it was going to be because he already has a child. I think you need to take steps to deal with your feelings around this before it builds up into resentment you can't control.
I honestly always stick up for SMs on here but, whilst I appreciate your feelings and emotions are heightened right now and I don't want to invalidate them, a lot of what you say in your posts I can't really get behind.
Perhaps it's just because I don't put a huge emphasis on Mother's Day but I don't really understand why it's such a big deal that his daughter is there. I mean really, isn't it usually just a brew and some chocolates / flowers and then a normal day? Especially when your child is too young themselves to really do anything. Your DH can still spoil you a little if that's what you want, give you a lie in, a brew, breakfast in bed or whatever. His DD being there doesn't have to mean he can't do that. Unless he leaves everything to do with her care to you in which case that's a different subject all together.
I actually am all for SMs being able to ask for some 'private time' to themselves with their partners in certain scenarios, the main one imo being when they have just given birth. I don't think it has to be some huge emotionally scarring event for DSC to stay with their other parent for a few days when their SM has just given birth like some posters here would have you believe. But I just can't get as worked up about something like Mother's Day.
Yes you should be allowed to have 'mummy experiences' to put it how another PP did, but those will look slightly different to how another person's will occasionally by virtue of the fact the person you married has a child with someone else. It just is the way it is. There is no one way to enjoy these experiences anyway, it's not less than just because it's not his first
although I think you'd find that hard to see at the moment.
I hope you're able to move past these feelings, it can't be nice for you to feel this way. I hope soon you can realise there really is no need to put so much emphasis on 'firsts' in the way that you are. First for you as a mum are lovely obviously but just because they aren't technically your husband's firsts doesn't mean he won't be appreciating them just as much.
My son is not my DHs first child. All our firsts he's already technically done with his ex. But our son is unique, he's an individual, he isn't the same as my DSC, so in a way we have had many 'firsts' simply because he's his own little person! And you know my husband absolutely adores him completely. No less because he's not his first child. Please let these notions go 