Yes, flip once...and you do probably have it turned up too high.
As you learn to get accustomed to your technique and flame, don't make your burgers too thick. You can always get to a point where you can cook a 1 inch thick burger, but why learn on burned dinners...take you time and start with something just about half an inch thick. Make sure it's firmly packed, but don't overwork the meat, either. Don't season the meat, I believe the salt will toughen it during the cooking process. I'm not opposed to seasoning the outside of the burger, once it's shaped.
Make sure the pan is hot. You should hear it sizzle when you place the burger on it. Watch it....when you start to see blood forming on the top, it's almost ready to flip, depending on how rare you like it. When you are satisfied with the amount of blood on top, flip it, but don't squish it. You'll force all the juices out of it. Put you cheese on now, right after you flip it, so the heat from the meat helps melt the cheese.
If you do a burger about half inch thick, and cook on medium to medium high, it should take about 3 minutes per side. It's not exact...but it's ball park.
good luck, and don't forget to tell us how it turned out.