I too suffer from depression. Or suffered, however you want to put that (since in my opinion depression will always be part of your life, you just learn to live with it). It was at it's worst some years ago when I had to take leave from studying and working for a year.
What I know of ISFJs (my mother was one, and my girlfriend is too (And what does that say about me then? ), some other people too...), they enjoy being in a role of a supporter. If they consider you as close friend, they'll never judge you. However, they do judge other people a lot, quietly. Should someone offend them, they say nothing... but are hurt inside. They often tend to expect people to behave in a certain way they deem to be acceptable. As they are usually humble and quiet, they dislike flashy person such as Class Clown or Superstar. I personally feel that their their greatest flaw is their inability to tell others what they like and dislike, and make others respect that. That's why they earned the nickname "doormat". However, for their benefit I must say that world would be so much better if there were only ISFJs. They just want to get along with everyone, and often do. I envy their ability to connect with people (not in flashy ENFP way, but in a way that everyone considers them trustable and honest). We ISTJ are honest when it's our duty, but ISFJs are honest because they just are saint-like.
But these are just my own subjective opinions of the ISFJs I've known.
And welcome to the boards, we kinda lack ISFJs here