I am getting married in 2 weeks and dealt with this my entire engagement. It was horrible. My parents are throwing me a blow out wedding, which I am happy about, but it came with these exact same strings.
These are the suggestions I have for you. Sitting down and talking with your mom may help, but for me it just made it worse. I found that when my mom would make ridiculous requests that just made me mad, made me cry, etc, the best way to handle it was to say, ok Mom, or somewhat ignore it until it came up again.
Many of these requests came via email from my parents, which made them easier to ignore. If they called me about it and I actually spoke to them, the best way to handle them was to stay calm and ask them how important having this is to them and why is it so important. Sometimes this helped. Other times, I made deals. I told my mom that I would carry the white bouquet that she had her heart set on me carrying, if I could get the color linens that I wanted. The linens were not important to my mom, but the color of my bridal bouquet was. We compromised.
What I learned was to stay calm when my parents wanted to change things that I wanted. When I got angry, lost my cool, and even lost it where I would start to cry because of how stressed I was, it only made the problems worse. Asking my parents why they really wanted (whatever it was) also helped because it helped me see where they were coming from OR in some cases helped them to see that it really wasn’t that big of a deal and we were able to come to a happy medium.
For things that I just didn’t get my way on and had to give in, I started writing them down so that when my parents made more ridiculous requets and for things that I felt very strongly about, I would remind them what I had already given in on, nicely and calmly told them why I really wanted (whatever it was), that I was so grateful that they are doing what they are for the wedding, but that it would really mean a lot to me to have (insert item here).
In the end, you will just have to accept that there will be things that you will not get your way on. Once I came to terms with this, and started keeping track of what I have given in on, it helped.