According to the HFL records she was born in Riseberga, Kristianstads län. However, the birth records for that parish do not have any births for a Bengta in all of 1811. She did come to Sireköping from Riseberga in 1837. There are no moving records for Riseberga for that time, so the trail goes cold there. A really keen person could page through the Riseberga HFL (2 volumes) for 1832-36 to try and find her. There's a gap in the records from 1837-41.
In my experience it's not uncommon for birthplace to be confused with the place a person moved in from.