you seem to have a lot of expectations about how fast trees grow ... i dont have any experience with these.. but 1 or 2 leaves.. every 2 or 3 weeks sounds pretty aggressive to me ... why do you think that is slow???

you talk of frost.. so you are in a cool zone .. i presume its potted ... but many of us in cool zones.. are a couple weeks behind due to a long cool spring.. that might be a reason why its slower than normal ... where are you/it???

its a tropical plant.. so i would GUESS ... it does not prefer bone dry soil ... so you have to make sure you offer enough water.. without rotting off the roots in a pot ... drying is a function of proper drainage in a pot ... so that might be intentional ... did you repot it???

what fert did you use.. and how much did you apply ...

a pic of the plant.. might help for us to spot some issue.. not addressed in your words ...

when you took it outdoors.. from winter inside.. did you properly harden it off to sun??? ...

ken

Please add a picture. Is it in the ground or potted?