Growing chillies

If the soil is not drying out at all in between watering it might cause flower drop. Also are you doing anything to pollinate them as there won't be any insects around to do the job? I've only tried chillies in a greenhouse and various critters do tend to fly in the open door in the summer. Use something like an artist's paintbrush, just give it a little light brush over each flower. I would have thought it's a bit late in the year to get any new fruits ripening though, unfortunately.

You may be watering too much, but you're definitely not overfeeding. I feed twice a week. Perhaps now the difference in temp between day and night is just too much, especially if they are next to or very near to a window. I have some at the flowering stage, but would not be too disappointed if nothing comes of them.