Hey mate, it sucks that you got pulled over on your first time, I usually put them in the dashboard while driving home from post office just to avoid this type of situation... I never got busted like this but I got busted by custom many times. No legal services were required, they just sent me a letter that the products has been seized, that's all.. in this case as it was busted in your possession and in your car means they have bit more to go on...
You can get some legal advice but I had my ex's brother a cop and we chat about it many times, he said the possession of any kind of steroids can get you charged as the cop will have to report for sure if they see or found something in your possession (also they will have to test it in lab to confirm the contents) But depending on amount (you had a small amount) I don't think you will even get a fine although you will receive a warning.. even if they call you in court (it won't go that far as it is wasting court time for a bit of testosterone) rarely if it goes the judge will issue you a warning only... If you had gears for whole gym

that's the other case hahhaha ... Selling and using is different, the amount you had is for usage and not for selling, if I were you I wouldn't worry about it, you can receive a warning and probably you will be on watch list and won't be able to receive roids on your address as all you local packages to auspost will be checked for sometime (fee months)
But this should NOT
- put you in jail
- give you fine
- have a criminal record on your profile
Thats what my understanding is from NT Laws and talking to the cop. NSW would be different? I doubt it.
Let me know what your lawyer says anyway