to pinkkhan Its normal! Basically Stretch marks appear because of sudden weight loss or weight gain. All you need to do is :
Drink more water
eat healthy and well
Apply olive oil after taking bath ( when body is wet)
Keep the process at least for 2 months .
You can use olive oil for your breast size as well.
Massage your breast with olive oil before going to bed or after taking a shower .
And also there are lots of breast exercises which can make your breast bigger !