Breast Pain at One Side

Hi, I’m a 20-year-old female and I started experiencing breast pain since 5 years ago. The pain were mostly on left side, rarely on right side. The location of the pain is mostly on left upper breast (close to armpit), lower left breast, occasionally sharp pain in nipple. It is mild, comes on-and-off, but disturbing. Once it happens, it lasts for about 10 minutes. I am not sure whether if its related to menstrual cycle as it also happens during normal days and mostly occurs in one side, but I do notice it getting more frequent and worse in 10 days before/during my period.

Also, I notice that when I’m stress (eg rushing to write an essay, playing an intense song on piano), my chest feels tight and the breast pain will occur again. Sometimes, when I lift very heavy objects, I might also feel the pain on right breast.

5 years ago, I’ve did blood test and chest X-ray and everything shows normal, just a bit high cholesterol. I also don’t have any medical conditions. I’ve done some basic self check, no lumps or changes in texture/shape of breast. But I notice that my left upper breast tissue is stiffer and larger than right side, and has larger axillary breast tissue.

Side notes: Since last year, I get heart palpitations and feels breathless occasionally. Done ECG before and the doctor said it’s probably due to stress. Not sure if its related but I wrote it down just for reference.

This condition worries me a lot and often affects my mood… What could be the possible cause? Should I get any specific breast screening? Please advise.