Check out the Remington youth models in 870 or 1187 Express. The youth model has a shorter length of pull, the distance from the trigger to the end of the recoil pad. This fits smaller women or kids better than a full size shotgun. The 1187 being a semi-auto will weigh a little more, but the extra weight and semi action reduces the recoil. Both of these are in 20 gauge.
I got my son a youth model 870 20 gauge and it's great. When I'm wearing a heavy coat, the 1" shorter stock helps me. Like he said, you might try the 11-87, it should have less recoil although it will be priced more.