Unreliable selfish mother

So my mother is one of those who makes great empty promises and shoves gifts in ur face so u forget how she's never there for u. Tells u she's coming to visit n then does a no call no show even tho u spent hours cleaning ur house n hours in the kitchen making a huge dinner...her excuse is oh well u never confirmed it (even tho I talked to her the day before and said I will see u tomoro) 
This is my second baby and it's been well over 6yrs since my first so I'm having another shower. I asked my step mother and my mom to work together to plan it. My step mother, not wanting to step on my moms toes said she will do whatever my mom asks her to do. My mom however isn't grown up enuf to ask for help even when help is offered. She would rather suffer than accept help. 
The problem is, this same thing occurred for my first shower so my step mom sat back and just waited for my mom to want her help. 2 weeks before the shower my step mom txt my mom to get the status and finds out my mom has NOTHING planned. So at the last min, my step mom put everything together. The only thing my mom did was bring the cake from the bakery that I tell her every year I hate. But she loves that bakery so she gets my bday cake from there every year even tho I hate it.
How do I prevent this from happening this time? How do I talk to my mom and tell her she's being childish and I don't trust her to do this on her own without hurting her feelings. 

Glow Resources

Let’s Glow

Glow is here for you on your path to pregnancy

Glow helps you navigate your fertility journey with smart tools, personalized insights, and guidance from medical experts who understand what matters most.

25+ million

Users

4.8 stars

200k+ app ratings

20+

Medical advisors