Between what percentage should hcg be leveled up by

I don't know why I am being paranoid but June 8th first beta was 2125 June 10th it went to 4252 then June 16th it went to 19002 and yesterday it showed 32,203. But the ER doc telling me my numbers look great even though it is shy of several numbers from doubling....someone plz respond and let me know if it always has to be doubled 💯% every 48-72 hours