I don’t think it’s your responsibility to make sure she addresses her problems with you and doesn’t bottle her emotions.

It’s possible she just wants to chat about other stuff and not necessarily post online in order to address her problems. For example I almost never post anything about any problems online. It doesn’t mean I never have any problems or that I bottle anything, I just usually have no desire to share problems online.

Also sometimes people get busy.

Friendships even if just online should be give and take. It could be that she feels she needs break sometimes. Honestly if someone sent me 1000 messages, I’d likely block them. I think you contacting her so excessively could be overwhelming for her?

You mentioned her seeing a therapist. Have you considered seeing a therapist yourself? Is it possible that being somewhat preoccupied with someone online takes away from your own life and perhaps your own problems?