This may be precisely the problem. Everyone sheds about 100 hairs a day - the hairs we curlies shed tends to get wrapped around the other curls and not actually come away until we detangle.
If you only detangle every 3 days - there's 3 days worth of shed hair just hanging out waiting to be pulled away - that's why it looks like you're losing so much.
Those shed hairs can also weave the other hairs together resulting in matting, knotting and SSKs (single strand knots). My advice would be to detangle every day, or at least finger comb to grab those shed hairs and get them out.