Hi Shazz,
I think a second opinion would be good for your peace of mind, now that the nurse has sewn the seeds of doubt in our mind. Also, as you unfortunately have a few things going against you, I would look at going to someone who specialises in PCOS. I just had a look at your current guys specialties and it did not mention PCOS so maybe you need that looked at a bit closer. Also I always think that if you are going to change, then change clinics altogether ie. try Monash instead then you get new scientists, new cultures, new everything which may just make the difference.
good luck shazz - you have got so close once, it must be very frustrating and sad to be making this decision.