You have to show your own to get a good trainer in boxing.
Doesn't make sense I know, but unfortunately that's how it is, especially in Australia.
The best trainer you could get right now is Gretchy at Boxing Works in the city (sydney), but he is $100 per session.
If you have the chops to actually compete with the pros OS though, he is a great trainer to have as he is connected with Ricky Hatton promotions in the UK and golden boy promotions through them.
To the first poster, it's not the weights making you slow, it's the 4 month break. How did you and your trainer think having 4 months off wouldn't slow you down?
If you are a big puncher, it wouldn't be a bad thing to go up in weight anyway. Work your speed back up and you should dominate if you are half decent. Esp here in Aus, the quality isn't much.