Get the pregnancy test where it shows the number and go off by that?
Sorry to hear that the nurse wasn't helpful. In our hospital the doctor would usually request an ultrasound to determine how far along the pregnancy would be. For injections, depend on ur area. for us here in the Philippines only tetanus toxoid is given, flu vaccine is optional.
Ig you could remember around when u may have started you're last period just count your weeks from then. It's a guessing game anyway, until u anyway actually get the measurement of the baby at the ultrasound. If your not comfortable w/ your nurse I would definitely switch offices now, but your ob/midwife may not be as bad. Doctor recommend that u get the flu shot, I'm opting not to, as I think the shot doesn't help anyway. Hope this helps:)