Greetings Alberto. If I were you I would not be concerned about the density on the left cheek. The hairs are still short so you can still see the skin, but as they grow longer the density of your left and right sides will become more and more similar. I think at 13 weeks they will most likely match. The example you posted looks like a groomed 4-5 month beard so I think you should let your beard go for that long and see how you like it. Your beard curls a bit and that will help a lot. Cheers and enjoy your new beard!