Climbing the ladder – French Macs

French Macaron
1 batch no food Colour but having the lite browning yellowish hue ( top right in box)
1 batch with yellow Americolor powder (1/8 tsp). Have a light yellow color

I’m trying to get a white Colour

Temperature: 300 F – 18~20 min longer no stick on the silicone mat. Small size

I tried a slightly bigger size but , was underbaked even at 23 min . It was total failure with sticky bottom .

Please help where I’m going wrong .