I found I had to organise my reading list because books slipped through the gaps.
I use my phone to keep a check. Every month I list the ebooks I buy and mark them off when I read them. I keep Harlequin and Regency Reads in seperate lists. And for some reason I don't list Baen - I just buy them to support the company and if I don't read them I don't mind.
Some months go well. e.g. November - 26 read out of 26 bought. However Harlequins that month 11/24. Regency Reads 0/5. So that's a total for that month of 37/55. (Not counting Baen.)
At the moment I'm finding I can't buy much that interests me so I''ll be catching up on last year's books.
I buy a book that interests me, then before I get to it I buy another one that interests me more. I did the same with paper books.