Hello aspirant. You can take any of the subjects in 11th since you wish to pursue interior design as after 11th it will be completely a different stream. Both of them play an equal role, but i personally suggest you to take mathematics because interior design is way more related with creativity and mathematics too. If you are creative enough to imagine with different combinations, creating something really new, imaginations beyond the circle, then go for mathematics. it would be really helpful. Else, go for psychology.

All the best

Regards

Nikhitha