Sometimes it helps to tighten the presser foot tension. It's the metal knob on the top, left of your machine. Righty tighty, lefty loosey.
A "seam jack" or "jeans jack," can help you get over those thick seams. Bernina makes on called a “height compensation tool.” Or you can fold some light-weight cardboard to a thickness of 1/16” to 3/16.” I've used an empty needle pack, too. I have a great tutorial on how to use a seam jack, but I'm not allowed to post the link.