Indirect way of monitoring E2 without blood test?

[Aragorn]

If you need to use an AI. Start low and increase slowly. You don't need to measure it in that process, you can go by symptoms. Once your symptoms resolved and it's stable, then you could measure E2 for reference.

That's what I'm trying to do, but still monitoring the number would help because overdosing causes same symptoms as underdosing. So far even 0.040mg (40mcg) of Anastrozole seems to have some effect. I think when I build tolerance - a higher dose will be required...