Easy-going means you friendly and relaxed, that you don't sweat the small stuff and have a good tolerance for other people's words or actions: you don't get upset easily.
Laid-back is the same so far but has an extra layer of irresponsibility regarding tasks which need to be completed.
Even-tempered is a person who is hard to upset or annoy.
In conclusion: You can be too laid-back if you don't work on your upcoming projects.
Easy-going is a combination of laid-back and even-tempered.
Even-tempered stricly talks about the personality, not their ability to complete tasks on time.