Regarding Different breast size

Sir/Madam

when i got married my left breast is little smaller then right one but after my post 2nd delivery my left breast becoming small why? any problem?

[ANewLife4Me]

It's usually perfectly normal for women to have one breast a little bigger/smaller than the other breast.  
As far as post delivery, are you breastfeeding?  I ask because I've read that one breast can produce more milk than the other.
Now if you've had quite a considerable shrinkage in one or it's changing position, I would definately see a doctor just to be on the safe side.

[Sqwills]

It may be due to the milk in your breasts after delivery. One side of your body is always bigger, also. Us humans aren't perfectly symmetrical.