For what it’s worth, I’m in my late thirties now and have been with my partner for 10 years. My parents stretched themselves and worked extremely hard to give my brother and I a private education, like you guys did for your kids. Should my partner and I decide to marry, we would NEVER expect anything towards the wedding from either of our parents - they did their bit when we were growing up and we are extremely grateful for it. We have good jobs and would have a celebration we could afford. I mean, a bit of money behind the bar for a few drinks on the day might be nice but nothing else!
But I also wouldn’t hide how expensive it is - I would definitely want to have a slightly shocked conflab about how much people charge for a few flowers or centrepieces as soon as the word wedding is introduced, never mind the venues, cakes and outfits! A bit like when you go to the cinema with kids for the first time and come out feeling like you need to remortgage the house to pay for it (don’t get me started on Legoland).
But it certainly wouldn’t be a manipulative attempt to emotionally blackmail my mum into coughing up any money towards it, it would just be to get a sympathetic ear as I shake my head and groan in amazement. Your daughter may not even realise her references have made you feel this way.
It sounds more like you feel a bit guilty, as you have been used to providing your children with as much as you guys could afford as they grew up and it’s hard to change a habit of their lifetime. My mum, especially, is struggling with that now (and that my bro and I are financially independent and are now in the position she would have been in at our age - so the roles aren’t quite reversed but…different).
Talk to your daughter. Tell her how you are feeling. And find out how she is feeling too (if she’s mentioning it, it might be that she is feeling a bit overwhelmed about it and could use some advice). Otherwise, you’re both just guessing at what’s going on in each other’s heads!