Please help! My left breast is getting bigger...

Hareem

Hi, everyone. It’s been a few days since my left breast became visibly bigger in size and touch. Both of my breast are normally the same size, they have been the same for years. I’m 19 years old, (20 in June). The left breast doesn’t hurt, and I don’t feel any lumps, my nipple also looks fine. But during the day when I feel discomfort in my left breast, I also feel it in my right breast. I’m extremely stressed out, and I’ve been overthinking. Vaguely I can recall noticing subtle size difference between my two breast for a few months or so, but I think I always ignored it. I have increased level of estrogen, I am also pre-diabetic, and I have been obese for most of my life. Please let me know if this is normal to experience, could it be premenstural syndrome, or does it seem much more serious?