whY CAN'T I STICK TO A PROJECT I JUST SWITCH BETWEEN 5 AND MAKE A TEMPORARY NEW ONE EVERY COUPLE WEEKS I JUST WANT TO FINISH SOMETHING

Only 5?

I get bored after finishing some part of a project

Try writing down a real milestone list with which features should be done when.

I have the same problem with hobby projects and find that if there is a list to check things off on it can help (not always all the way).

And if its a practical one, try getting some non developer to test it and give feed back.

That can bring positive pressure :D

I try to make the minimalistic possible and then extend it further, that way you have always finished projects ;)

That sounds so much like me...

It isn't a real day at work unless I work on three different projects.