Struggling with a Friendship That Disappears

I’ve been struggling with feeling lonely a lot lately and today I was supposed to get together with my closest friend who I haven’t seen all year yet. She’s been dealing with a lot of depression and traveling a lot and I’ve been struggling with ptsd so we never had time line up where we both felt okay enough to do something. Today I arranged to have my kid stay with my parents and have my friend come over. She said she could hang out anytime this week because she had no plans and I told her today or tomorrow id like to hang out. She then sleeps in until the late afternoon and texts me a couple times and then stops messaging so never told me yes or no to hanging out. So we never got to do our plans. This has happened a few times with her and I know she has a ton of mental illness struggles she’s dealing with among other health issues which I can relate to but I feel like sending a message saying you can’t come over today would’ve been something doable if she was able to send me other messages. I don’t really know how to handle a friendship like this where they disappear from texting for weeks at a time or don’t hang out with you for months. Just has been something making me feel more lonely lately. Especially because I have been going through a ton of high stress situations and I’d like to talk to one of my friends about it but I only have 3 friends and like none of them have really checked in on me lately so I don’t really want to talk about things like this with them.