I want my old friend back. Any way to make that possible?

I’m 25 now. At ages 15-17, I had a best friend who I went to school with. Around 17.5-ish, I stopped being friends with her because she never spoke up when people talked badly about and bullied me. She said her anxiety stopped her from doing it, and at the time I didn’t believe anxiety was real, so I didn’t accept it as a valid reason.

After we stopped being friends, we remained friends on every form of social media. She continued to like my posts and respond to my stories. About a year ago, I messaged her and apologized for not being a better, more understanding friend. And I explained that I understand how real anxiety is now (from personal experience) and that I feel bad for not understanding at the time. She thanked me for my apology and continued to interact with my posts as she always did (and probably more often than before). Now, I’ve started also interacting with her posts and even struck up a conversation with her (before, the conversations were just responses to each other’s story instead of being out of the blue). But I’m not sure how to get it to the point that we talk regularly. I’m not even sure what to talk to her about. I just want us to be closer. Is there anything I can do? I obviously can’t say “lets be friends again” lol. But what can I do to make that even slightly possible?
Thanks!

​

TL;DR: I (25) ended a friendship at 17, but we remained friends online. She continued interacting with me and I recently apologized for being a bad friend. She accepted the apology and now I want us to be closer.