b12 shots are great. you cant overdose so go for it, its super cheap also and b1q2 is a very important vitamin for lots of processes in the body.
test can be increased but you risk some side-effects. muscle building could be a bit bigger but everyone reacts differently to tren. some cn go to 1gram of test on tren and no issues and some need minimal test with trenbolone. If the results are good i wouldnt increase testosterone, i would add something like masteron to increase free test (the really active part) and this works great with tren as well