Will you definitely be 'shooting-up' during a thaw cycle? Could you get them to monitor you and see if you can get by on a natural cycle?

The Monash pharmacy would be able to give you advice on the drugs passing into the milk. They are very helpful.

I was only doing a natural thaw cycle and I was using OPK's so no drugs. My FS said yes, give up BF. He accepted that the hormone changes due to breastfeeding were not necessarily going to impact the cycle, and seeing as I had partially weaned DS1 and got AF back, he was none the wiser as to whether i was secretly breastfeeding (which i was, as i found weaning SO painful and the easiest relief was a quick bf )
I asked at my ABA and although they knew very little about AC, they did agree that breasfeeding does impact fertility. I sought out advice and in the end I decided that i wanted to give up BF (the day before the transfer ). I did conceive DS2 that cycle, which was amazingly lucky. I'll never know if BF made a difference, but my choice was right for me.

ETA - if you need the phone number for Monash (or is it RWH?) I'll find it somewhere...