Baby shower issues, advice appreciated

Barb
Do u feel that if u are paying for ur baby shower stuff u should have a say in your baby shower planning
So I'm having a lil situation, people keep telling me that my baby shower Should be a surprise n am not supposed to know anything about it n blah blah blah
But here's the thing they wanna plan it but they aren't the ones paying for most or all of it, we are well more likely husband is because I'm a stay at home mom n wife so he's the bread maker here n my husband n I picked a theme we want so my sis whose helping plan is ok with keeping to that theme n is willing to plan the baby shower with my husband n she said that she'll respect my wishes as to what I like n don't like but she doesn't want to give me any other details about anything 
Then I have my I laws who want to be involved in it but my mother in law keeps trying to push her theory on it supposed to be a surprise n I'm not supposed to have any say in it at all I told her that I want to be involved because this is my 3rd n final child n I wasn't involved in my 1st borns shower planning n I didn't have one for my 2nd born n she said well that's the way it's supposed to be, it's supposed to be a surprise, I told her yea but it's not a surprise at all I already know what a baby shower is n what to expect then she said well it's tradition n I told her well we don't always follow tradition n we like to start our own traditions right babe (telling my hubby, he didn't disagree) so she stood quiet.
My in laws are only probably going to provide food n my sis told me that she wanted to help with the decorations 
So here's how I feel if I (my husband) is paying for the location, most of the decorations, most likely most of the food, the baby shower favors (I want to make them) n the cake then y in the world can't I have a say on the cake I want, the decor I want, the place I want n the food I want included like I'm paying for it there for the one that's truly planning it is us (my husband n I) so wth is the problem 
The way baby showers go is the person whose planning the baby shower is the one who pays for everything unless they ask for help from others so y am I expected to pay for it if I'm expected to not be involved in planning it
Do u feel that I am wrong in thinking/feeling this way? If so please let me know but not in a bad way, let me know in a way that will help me to understand the others point of view