Well those aren't BMW wheels for certain......
If you want to see what wheels are fitted as OEM by BMW then you could have a look at
this site which offers OEM wheels (with or without tyres) at non-OEM prices. This will at least give you images of all the OEM options.
You can then decide which way you might want to go. Note that for OEM 20" wheels you will need to fit extended wheel arches as the tread will exceed the limits under the Construction & Use Regulations (tread must not extend beyond the wing with the wheels straight ahead and checked at the 12 o'clock position) and your front wheels look awfully close to that although it may be an optical illusion from the camera angle. This is NOT an MOT item, although it ought to be.
If you don't want to go to the expense of fitting extended arches, then 19" are your option. The 19" and 20" OEM wheels are 'staggered' if you hadn't already discovered that..
Richard