It sounds like at the core this might be about expectations, you are saying you’d like to meet up once a month but she seems like she feels differently?

I’ve got to say there’s none of my friends I see as often as once a month, in fact one of my dearest friends I only see a couple of times a year but that’s okay with both of us. It’s whether your expectations match or not I’d say and whether you’re prepared to compromise and accept seeing her less.

She doesn’t sound like a direct communicator and I understand that can be frustrating because you sound like a more direct communicator. So there seems like a mismatch in communication styles too. Again you can’t really change that, although there’s some phrases you can use such as asking directly “What works best for you?” You may already be doing this however.