Assuming you catch the disc while airborne (and that before you were in-bounds, otherwise it doesn’t matter how you land, it will be out the moment you touch the disc):
11.3.1. An airborne player retains their in-bounds/out-of-bounds status until that player contacts the playing field or the out-of-bounds area.
When you land it’s the first point of contact that counts (in your case it’s both feet). If any part of your body (or disc) is out-of-bounds, then you are out-of-bounds.
In your situation to stay in-bounds you should have landed with your left foot first.