What bra size should I get?

Ok so I wear a “small” in this comfort brand. They are kind of loose so I thought a 32B would be good but no. I tried to get a push-up and it was way too small... I’m so confused. And the push-up was cheaper than my flimsy ones.
What bra size should I get?
What bra size should I get?
What bra size should I get?
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