Need some help identifying these brown/gold spots,...

If your diary is accurate and you are giving .79 gallons every day, then I would say you are overwatering. When a plant is 3 weeks old in that size pot it should be taking a good 3-4 days to dry that pot out. Not waiting until the pot has dried enough will certainly cause spots to appear, and it would also explain why you had them when they were younger also. She will show you if she gets too dry, so many people overwater, remember most of the time less is more. Wait until that pot is very light before watering. Happy growing.