Thanks for using health care magic.
If you have had two negative reports for pregnancy
, then it is unlikely for you to be pregnant.
Breast enlargement has nothing to do with your pregnancy.
There could be many causes for delay in periods for 2 months. Probably you need to get a USG done to rule out the medical causes behind this delay.
Regarding chest burning pains, you should take an an-acid such as ranitidine
Hope I am able to solve your concerns.
Dr. Srikanth Reddy