MrsWhite--welcome to the board from GA.
I am sorry that you are frustrated with your quilt. I think you are better off using the same weight of muslin throughout your entire quilt, including the borders.
Where did you buy your original muslin? Did you return to the same store to buy more? Are you sure that what you purchased the second time is muslin? (I am not trying to imply that you do not know what you are doing--there are other fabrics that are the same color as muslin, but actually are not and sometimes they are in the same place in the store) Shopping for muslin is sort of like shopping for sheets--it is all about the thread count. If you buy a cheaper muslin that is a looser weave it is going to shrink more. If you buy a muslin with a higher thread count it will shrink less.
Can you please post a picture of the blocks you have made for your quilt? Maybe we can help you with some ideas so that you are not so frustrated!!
Good luck with your pregnancy---when are you due?
My husband was in the Arny for 30 years. We were stationed in Colorado Springs for 2 of those years. Unless it has gotten hotter and more humid there, you will not need air conditioning in the summer.