1. I’ve got enough saved to live comfortably until I get settled in.
Little does mom know that your idea of ‘comfortable’ is Couchsurfing and raiding your host’s fridge for food the second they go to work.
2. I still need all of this stuff I am cramming into your closets/attic/basement/garage.
I call bullshit. You are attached to it emotionally. You do not need it. There is a world of difference between the two. I wager that you will not care about all of your old belongings when you are halfway around the world, perfectly happy (and probably even happier than ever) living with 5% of your previous possessions. A few boxes of old photos and a few keepsakes you want to keep in mom’s attic, fine. But when you come back, (if you come back!), you will probably shake your head in disbelief at the stupid stuff that at one time you could not part with.
Do your family a favor, bite the bullet, and part with as much as possible before your trip. They might love you to death, but not even family enjoys babysitting all of your shit.