But when i disconnect the ch340 and power on the esp the red and blue leds are flashing and the esp won't boot. When i leave the ch340 connected in the breadboard (not even connected to my computer) it just works. So i believe i need to do something with the rx and tx wires, but i know too little about this to figure that out by myself. Thank you in advance for your help.
EDIT: i found the solution after all. For people that also have this problem -> The capacitor that i used was too small. Appearantly the capacitor that i used was only 1 µf, and it must be 10 µf or more between 3.3v and ground, and as close as possible to the esp8266.