When you say "I don't know if it's something I've always had," but then use words like "larger" or "darker," which imply a comparison to something else, if you're not comparing the appearance to what it was like before (because you can't remember), are you comparing to your other side? Do you think there is a chance that the areola might have also been always larger on one side than the other and you just didn't notice, or do you think this is a change?
Women's breasts are often not symmetrical. A lot of women have one breast slightly larger than the other. If that's true for you, it seems like a larger areola would go along with it. Also, breasts definitely change if you gain or lose weight. What is your age? Your breasts might not have settled down to their final adult appearance if you're under 21.
Also, you say "my health anxiety decided to overwhelm me." Have you gotten some counseling help for that? Because it can lead you down so many rabbit holes that your life will be very uncomfortable until you address it directly.