Bringing a number across to Boost is fairly straightforward but it needs to be done when activatingthe new SIM not after. Instructions can be found here https://community.boost.com.au/t5/Activations-Porting-KB/How-do-I-bring-my-existing-mobile-number-an...
It sounds like you have already activated, if so contact Live Chat and they should be able to help you with the process to transfer your number.
It can take 24-48 hours for the number swap to complete. If the number still isnt active after that time, I'd suggest contacting
Boost Customer Care on 125 8881 or speak to them via Boost Live Chat