First, welcome to the forum, and good to have you with us!
I think this is a very individual thing, and varies from person according to your vaping style, how you inhale, the equipment you are using, etc.
If you feel good, are not having any symptoms of too much nicotine, and don't have terrible urges to smoke, you are probably doing just fine. I've been vaping for about 4 months now, not smoking at all, and I don't pay much attention to how much juice I use. I have several different tanks with different flavors that I rotate throughout the day, so I couldn't keep track even if I wanted to.
I feel great, and I'm not smoking, so that's good enough for me.