Period Only Lasted One Day??

‼️‼️‼️Please excuse the TMI photos.‼️‼️‼️‼️‼️‼️but my period started December 6th (it’s normal date) and only lasted a day? The second photo is December 7th with hardly any blood. (I took photos because I wondered what the stringy clot could be)but the next day my bleeding just stopped🤔I took a pregnancy test the next day and it came back negative. I’ve been waiting to see if my period was going to come back on and it hasn’t and is almost time for my next cycle. My period is like clock work and comes very regularly. Every 28 days for 3-4 days. Can anyone explain please I’m very confused and a little concerned.