Hello friend,
It can sometimes be breeder size or many autoflowers tend to be somewhat smaller in those first few weeks. Personally all my fast buds grows have been smaller, but that may be because of my growing methods.
The only specific thing i can see from your diary is the daytime temperature of 99 degrees. If you were outdoors I wouldn't say that's a problem, but indoors it's a bit high and can definitely stunt the growth. Keep ventilation high, a nice breeze and a good air exchange.
Happy growing. ✌️