Thank you for your answer. The 5 V regulator is good idea. Unfortunately I have to use a breadboard (project for school)... So I will try to minimize the currents as far as possible.
I think my suppy can handle this. I use 3x 3.6 V Batteries with a protection board (Datasheet: https://www.akkuline.de/media/pdf/1b/55/bf/INR18650-15M.pdf).
Also, I switched something up. The USB-TTL Chip gets hot! It is a CH340.