SIL baby shower...things are a little better

I am feeling a bit better now about the baby shower event for my SIL. My middle SIL called me and told me they were going to change the shower date so that I could go. I told her how I was hurt that her mother just "told" me the date and didn't ask if I would have plans. She said she agreed that it wasn't right. Since then I have talked to my MIL and we are on friendly terms again. Sometimes she is just so hard to deal with she is always doing things like this to me and I always am the one to suck it up and just have to let it go. I really like to plan and do things for parties like this. I'm a graphic designer so I LOVE to design the invites and do the favor tags. I volunteered to do solitary functions where I can just work on my own and not have to hear all the happy baby chatter. I'm designing the invites, making the favors, and buying/making gift basket prizes. Its the chatter of baby joy that gets to me...making me realize how much I am going to miss in life not being able to experience a pregnancy myself.  I just can't deal with the talking of the baby or seeing my SIL's big belly. I know I am going to have a VERY hard time at the shower but I will go. My plan is to sort of hide in the background and maybe try to be behind someone's head when she is opening gifts so I don't see much. And if I get too upset I will go to the bathroom and cry. And if I feel I just can't take it I will tell them I'm not feeling well and leave. I mean who voluntarily tortures themselves?