Questions on follow up

So I got my biopsy results back (b9) but with some quirks I guess. They found atypical hyperplasia and two nodular lactational hyperplasia or aka lactational adenomas.

They've followed me for about 4 months now.....due to very high breast density and fibrosis the adenomas don't show on ultrasound at all, despite being extremely palpable and large. 

They said even though the adenomas haven't changed in the last 4 months I am showing a lot of progression in symptoms such as deepening and new dents, dimpling and nipple pull.

They want me to wean the baby and to go back in 2 1/2 months again for a likely breast MRI. 

Two weeks after my biopsy I developed another third but much smaller lump. and a new indent. Should I call and inform them or just cross it off my mind until then.....and does this sound like a good plan of action? They said the MRI would be less effective while nursing ....and both ultrasound and mammogram are ineffective too.  My biopsies were blind and she said that doesn't help rule bad stuff out as well as if it was ultrasound guided.