As the sentence drags on longer and longer, you feel the narrator trying to glean just a bit more of your focus and attention. Her unwillingness to end the sentence and give you a moment to retract and catch your breath shows how desperate she is for connection and makes you literally experience the same feelings of those around her.

All of the little qualifiers and clauses show how acutely self-conscious she is, always amending and curtailing her expression of herself. It also shows how self-aware of her own negativity she is. Many of the extra clauses go out of their way to show that she is aware of the positive aspects of things.

But that in turn just reinforces our perception of her as depressed because we see that while she is aware of all of these positive things—having a support system, the expertise of her therapist, etc.—we also know she is depressed and her depression must be profound to persist in spite of all those good things she laboriously lists.

Prose like this is exactly why writing in the first person can be so powerful. You get to read the story, and the way the narrator experiences the story, and the way the narrator chooses to tell you how they experienced the story, and the unintended (from the narrators' not author's perspective) things that sneak out around what the narrator is aware of choosing to say.