Another Sauvignon Blanc question.

I've racked s Sauvignon Blanc off lees after primary and secondary
fermentation. The wine looked a little less opaque and more
translucent which I interpreted to be a decline in yeast population
and a signal for the end of sugar fermentation.

I racked and added 1/2 teaspoon of sulphite to the 4 liter demijohn
and 1/4 teaspoon to the 23 liters carboy. I still see bubbling from
the carboys. Is this CO2 or is malolactic fermentation going on? My
pH probe is broken so I don't have a pH measurement. I'll measure SO2
soon and report, but thought I would ask the question anyway.

I want to inhibit MLF to try and replicate the New Zealand style of
Savignon Blanc.

Any advice?

Dan