I would say your bottoming out issue is due to the more aggressive offset of the wheels and not to do your shocks/springs combo.
Looking at the width of the wheels you could have gone with wider tyres but that would exacerbate your rubbing issues.
I think your best options are as DRedman45 said.
Getting the Eibach pro kit will lower your car even more than the BMW Performance suspension has and you'll have even more issues with rubbing.
If the above options aren't for you then I would say that your only other options are to either change wheels to a less aggressive offset or add more negative camber.
Btw, is it the front or the rear which is rubbing?
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