Your driving pattern of a lot of drive cycles, but short drives indicates that you should change your oil more frequently. Your owners manual should list a time period in addition to the miles and end with “which ever comes first”.
Your BMW requires a special oil that meets European standards. These are more rigorous than US standards so make sure you are using the correct oil. Not many oils sold in the US meet this standard. If you are using a basic synthetic oil from a big box store or common autoparts store, then you have to change the oil more frequently, like 7500 miles. That should also be in your owners manual.