Water ultrasound - please help need advise re. triphasic pill

Me

Hello Ladies,

I am on cycle day 6 and am waiting to schedule a water ultrasound. My nurse prescribed me a tiphasic pill plus doxycicline with no instructions. Here are my questions: Am i starting the pill pretending it is day 1 or day 6? Also when am i taking be doxycicline? Now? After the water ultrasound? I feel lost. My nurse keeps dropping tbe ball on me. I am turning 40 in a few months and i kerp losing cycles because of sloppy communication on their end. I hope someone on here can help.