First of all, get rid of the foil...it only creates hot spots. It magnifies light and causes little white/yellow spots.
Second, you should never grow more then one plant in a pot. When they are in the same pot, they are competing for nutrients, root growth, and water.
Thirdly, dont chop off bad parts of the plant...let it always fall off.
Start over, and put one seed to a small 12oz cup. Once the plant is about 4 inches tall, put it in a bigger pot.