when you feel you're incapable of doing things, just think about all the things you can do! Better if you could write them on a piece of paper. Read it many times until you realize that there are other things that you can do!...This doesnt give much but i know it would make you feel better.
now, when you feel incomplete, remember that no one is perfect and that others are also feeling the same way sometimes. There may be times when you ask yourself why you cant have things others have. And even how hard you try to get them, you still cant. Bear in mind that you cant have everything. Not all of your wishes come true for it was never meant to be yours. Learn how to treasure all the things you possess. And you will feel how happy it is to be complete!