I’m totally beginner at this gardening thing and every google page has different advice. I built in ground garden beds / raised garden bed hybrid and planted two pepper plants and one butter crunch lettuce. The peppers are going great - lettuce not so much. I planted them all from starters from Home Depot. It’s been about 8 weeks since planting and the lettuce leaves kept getting yellow on the bottom and the lettuce head looked pretty full? so I just harvested the whole head. Now I’m worried it was too soon to harvest and I’ve killed it. Any advice?