Shorter Period & Brown Blood

We are TTC #2. Period showed up on the 8th after having sex the entire week of my fertile week. Got a positive opk on the 23rd! My periods are usually super heavy for 2 days (ever since having my first baby) like have to change tampons every hour or 2. So when my period showed up it lasted 2 days and mostly brown blood, never even filled a tampon. Also way more bloated than normal. Anyone experience this? My periods are usually all textbook the same and always regular. It's so weird!