Your system makes sense.
I don't trade but I'm often buying more as the price goes low. Determining the low is the tricky part.
It's all about price and I just look at a 10-day chart and make a line at the high and a line at the low (the ceiling and the floor).
The line in the middle is "the buy-line" or "the green-line."
So - if the 10-day low was $3,000 and the high was $4,000 the buy line would be $3,500. <=== When the price is below that number it's time to get ready to buy, but you're waiting for a bottom and then a strong upward trend.
It's been working for me and I'm going to give your way a try too.
PEACE!