Look at The post " breast pain 2 years after surgery". Some helpful comments there. I finished Radiothreaphy back in April and still have funny lumps but my breast surgeon told me all was definitely ok. I even have soreness and lumps in the left breast which was cleared back in 2015 which I received the diagnosis on the right breast. Some many weird things happen after treatment and as you will have read before we are all different.
its natural to worry after all you have been through but I guess we have to trust our Drs and specialist.
This may sound funny but I regularly massage both breast and talk to them!! O dear. I only have small breast and I find it better, when possible, to go without a bra.
Have you been able to start exercise yet? I've just started "passive" yoga and it's brilliant.
take care,
Anne-Marie.