Choosing the right size implant depends on any number of factors all of which require an in person exam. However, I always advise my patients not to focus on cup size as they vary so much between bra manufacturers and instead on the look they want to achieve. Best, Dr. Nazarian
Since very individual processes pain differently, it is impossible to comment on what is normal. It is common to have asymmetric pain. But since yours on the one side seems to not be diminishing, I think it would be smart to be assessed in person by your surgeon. Always best to err on the side...
What you are describing is probably caused by the implant pushing on certain nerves and is perhaps worst at that time of the month due to hormonal swelling. Best, Dr. Nazarian