I have the same question AnnieBrooke has. If you are fingering to the point you no longer get very excited or wet doing it, maybe take a little break.
Are you saying that as you have more events in a day you seem to have no discharge? I don't think that sounds like anything to worry about. it just means your body is used to what you are doing and doesn't 'juice up' as much with the later events.
Just be sure to keep your hands very clean, including under your nails. This has nothing to do with your discharge amount but with the number of times you finger yourself -- as that number goes up, the chance for introducing bacteria into your tenderest tissues (via your hands) also goes up.