wow. I think I would be the same way as you right now! a lot of young people are changing weddings around like crazy. girls having brides-men instead of brides maids etc...

I personally don't see anything wrong with a yellow dress or cupcakes instead of a cake or any of the other things people are making traditional now a days.

Is your mother normally like that? Seems like she should want whatever is best for you and whatever makes you happy and, no, I don't think 8 months is too short of time to plan a wedding. I don't really see anything wrong with the ideas that you just said or the way you went about them.

A lot of people feel uncomfortable flat out asking "what are you contributing to my wedding?" and different people have different customs of who pays for what etc... so sometimes it's best to put it in a way that doesn't seem like you're making it about the money.

Like saying something to the effect of "my friend (insert name here) said she wanted to buy my wedding cake but I wanted to ask you first to see if that was something you wanted to do with me". That way it seems like the main motivation is making your mother involved and not you scrounging for money.

Another thing is that a lot of parents think that, if they contribute, that means they can pretty much run the wedding. I have been engaged before and the only thing I let my parents have any monetary say in was my dress because my mom and dad both have good taste when it comes to that. but stuff like invitations, brides maids etc.... I was paying for because I knew they would pick something I hated and I couldn't say a word about it if they were paying for it.

So really, I don't think you did anything wrong but you know your mom better than I do. Those are just a few suggestions I have from dealing with it myself once. Good luck with it!