Asking for gifts

A bridal brunch isn't a gift giving event, so although your mom is asking what you might want, the guests likely will not. A shower indicates gifts, a brunch doesn't. It would definitely be weird to put your lingerie sizes on the invitations for a lunch.

First, money IS a gift. It's fine to want money but it feels disingenuous to say that you don't want gifts but do want money.

Anyway, I agree with Caytlyn that a bridal brunch isn't usually considered a gift giving event (as a shower IS), so no mention of gifts should be included in the invitation. People might not have been invited to a bridal brunch before and might just assume it is a shower and bring a gift out of worry of showing up empty handed. There's nothing you can do about that other than to thank them graciously and set the gifts aside so as not to make the guests that "followed the rules" not feel bad.

All of that said, if people ask you or your mom directly where you are registered or what you would like for your wedding, it's completely fine to say that you aren't registered but you are saving up for a home. The key is to only give that info when asked.

It is rude to ask for gifts. It is rude to ask for money (which is a gift). Don't register; people will get the idea.

Well I would definitely NOT put the bra/panty size on anything I do think that that is a little weird. I If your mom is planning it, people will probably ask her what you want and she can let them know. But I definitely wouldn't put anything about cash on invitations or anything

Don't volunteer anything. When people ask you, blush and say modestly that, well, you're saving up to buy a house because you have so little space you can't even fit in a wedding present. Your mother can convey the same message if she's asked, though she doesn't have to blush.

Just to clarify, you have already asked for money via your wedding invitations? If so, I definitely wouldn't be mentioning gifts (again, money IS a gift) in any other context other than people asking you directly where you are registered/what to give you. People can ask but that doesn't mean you are wrong for nothing creating a registry. Just smile and say you aren't registered but are saving for a home. Repeat. Don't read anything more into their questions or feel pressured into changing your plans.

It's beginning to sound like your local culture has lingerie showers (the bra and panty thing on invites). This isn't something I am familiar with AT ALL, but that would account for the 7/8 people mentioning it. Just because it's common where you live doesn't mean you need to do it. Continue with your plans to attend a non-gifting pre-wedding party that your mother is hosting. There is nothing wrong with any of that.