Hello, I'd like to help you with your question.
If you are suffering from Dysthymia
and you have bouts of deep depression, then it would be normal for you to feel like you are different from others and have parts of your life missing. Depression can take your desire or even motivation to have those things away. Plus just by having depression, it can take over your life and "steal" parts of it from you. Just as any illness does with anyone who suffers from a chronic illness like MS, Cancer, heart problems and emotional issues for example.
It is actually very normal for most people to compare themselves with others. Even if you don't have depression or fight a chronic illness, the comparisons to others is a common feeling. But comparing yourself to what you see in a snapshot of someone's life really does not give you the whole picture. These people may seem happy, but most people are not what they appear to be. It is not hard for most to pretend for a night that everything is fine. But in most people's lives, there is some type of pain, deep hurt or other tragic circumstance. So if you see someone you compare yourself to and you feel you come up short, then you may not have the whole picture of their lives. While they may have things you do not have or lost due to depression, they may also not have things you do.
It might help you to look more at those who are less fortunate than you. Just by seeing all that is lost by someone who has mental disabilities such as limited intelligence or someone who is addicted to alcohol or drugs, you can see what they miss out on as well.
You can also look at ways that you might add
more to your life and feel less like you lost parts of it. Consider volunteering if possible. Or small acts of kindness. Even a one time act of reaching out to someone can help you to feel that you are more than just a person with depression. You have a lot to contribute and as a result, a lot to gain from it.
I hope this has helped you,