Drama over baby shower :(

Christine
I just need to vent. I'm due June 19 and I'm scared. I'm scared of giving birth in general. I know that women all over the world have babies every day, so I know it will be ok but I'm really scared. 
My mom and mother in law are working together to give me a shower. My in laws have a history of being very inflexible with their schedules due to their jobs - when we got married they basically told us it had to be one of two weekends out of a four month span. They are nice people but can be hard to deal with. 
I would like to have my baby shower in April. I think it would be at a point in my pregnancy where I will still feel relatively good, and will give me plenty of time to get things set up even if the baby comes early. 
My mother in law told my mom today that she wants the shower to be Mothers Day weekend, which I think is ridiculous - I don't want to take up my guests' holiday weekend - or another weekend in May. She told my mom that no weekends in April are ok for her, and she prefers it to be a Sunday so that a friend of hers who observes the Sabbath can attend. I also really don't think it should be Easter weekend. 
So... That basically puts us at a weekend in March? I'll be 27 weeks. Is that too soon? I'm just so frustrated at my mother in law's inflexibility.