Please Help..dead Line Real Soon...

Hey! Okay...My 14th birthday is coming up and my cousin marissa`s 10th birthday is the the 30th of august which is the day after mine. And on her birthday there is this wedding for our couysins, so she won`t have a birthday that day so I volenteered to share my birthday. We both are not going to have friends over because she lives in mccloud and I live in redding and she is coming here for the birthday party and if I had friends over it would be unfair to her. Why you ask? Because she can`t bring her friends down because with all are family coming for the wedding there will be no room at anyones house...so we are only having family. And we don`t want to have a theme. Something cheap and simple. What games do we play though? What should we eat? What about apitizers?? And invitations. It puts all the stress on us!!! So...If you could help us please. I love planning also...oh and do you know if an ice cream cake would be cheaper or more expinsive. Okay thank you.
Sarah