You missed picking which patient to save, but you will still get the star stone when you eventually catch up to Evelyn.
The portals are opened in order (with a choice for the elemental halls), so the hall of heroes is second regardless of which star / blood stone that is. It will just take a little longer to get to. There is a star stone not too far outside Cyseal that you can reach quickly if a character can sneak or uses invisibility to bypass a couple opponents.
Just north of the city, head east and cross a bridge into the the fire area, then sneak along the cliff leading north and slightly east. There is a waypoint that will let you return without having to sneak again.