Yep, Straid is in The Lost Bastille. You get a branch after the Lost Sinner, probably where yours was from. There are a couple in Harvest Valley. And one in the Gutter (did you kill the Rotten? This one is pretty hard to miss). And one Brightstone Cove (after Freja). Without spoiling too much, there's another boss soul merchant who you'll need another branch for. You can get enough branches in one playthrough to unlock everything, just a matter of finding them all.