Hi Greg
I don’t do the Instagram thing so don’t know much the expected etiquette (Just googled that and apparently thier are a lot of suggested rules)

We live in a world with a lot of focus on immediate gratification. I.E when we text or such we desire a immediate response and become agitated (making up what if stories) when that desire isn’t met.  But why should that be?

Not that long ago persons in your situation would write letters with weeks in between. The anticipation of receiving a letter can be enjoyable….

In your shoes I might approach the Instagram thing the same way. This will require you to be able to communicate your boundaries.  Let her know you would like to continue communicating with her without the expectation of immediate responses… as if you were writing letters a suitable delay could be agreed on.
And perhaps a promise that if either of you wish to stop the communication you will let each other know. (no ghosting)

In Buddhist terms – What is causing you the headache is your desire and attachment to wanting what you want right now which has very little to do with this woman. She isn’t giving you the headache your are… Imagine enjoying the communications without such attachments.