I would ask to speak with someone different, or just book an appt with the receptionist. REALLY they cannot deny you an appt if you have concerns, so don't even ask, just do it. Then you can go over everything with your doctor yourself and not go thru a "middleman" if that makes sense.
I don't understand your concerns exactly? if it's because you're starting 5 days earlier, you haven't officially started yet... I'm sorry but a spot is not considered your CD1. I've had numerous doctors and nurses confirm it is THE 1st day of REAL bleeding. (btw do you know who she is? Call and ask for the head nurse to talk to!)
If it's about when your period is starting, do you have any infections going on? You said you're on antibiotics...
Are you under allot of stress, more so than usual? That can create your cycles to go out of whack for sure.
What is the pattern they have been in for a while, what is your norm? When did it start changing from your norm?
Your AF can be wacked out for so long after a miscarriage... mine had never really become "normal" they fluctuated days for CD1 and O days.
Write down your concerns, put details of what your cycles have been doing the last 6 months after your loss and everything you can think of that you would want to ask or talk about at an appt. If you're not satified how you're being taken care of I would do 2 things... complain & get a 2nd opinion!
Hope this helps!