My dear there is no real way to measure or grade oneself on being a good parent. I also understand the stress and depression part of parenting.
Here are a few sites that I really want you to visit and study.
http://familydoctor.org/online/famdocen/home/children/parents/behavior/368.html
http://loveourchildrenusa.org/nurturingparent.php
http://www.mommymoments.com/t1.html
http://www.bbc.co.uk/parenting/family_matters/you_parent.shtml
I have faith that you are and will be a great parent. Wishing you all the best.