NO WAY ARE YOU BEING SELFISH SPOD!!!!!!
Your and Dh's wishes are certainly first because happy parents mean that you have more to give your new baby, and all of you come first.
You should tell people (mother included) to call before turning up, and if people are going to be plain rude enough to turn up anyway, 2 hour drive or not, then thats their tough luck. Get a doorbell that you can turn off and enjoy your special time together.
Don't let your mum arrange your sister's visits, arrange them yourself, and make sure your sister knows that if your mum calls her trying to change things that she should check with you before accepting the changes. If your sister has a daughter did she go through the same stuff with your mum, maybe she would have some tips to deal with it?
People turning up when I wasn't ready when I had DD ruined those first few weeks, I was finding it hard to b/f, I was tired and emotional. I wasn't ready to play cheery hostess, and believe me if anyone tries it this time round I will let them have it (assuming they were already told not to come over).
If there is no reasoning with your mum then I think you will have ignore her or just be ready to be rude. You shouldn't have to fear what you have a right to, your own life and time.
Can you tell I'm psyching myself up for any upcoming confrontations?