I smoked like you orly1777, about 70 a day, maybe even 80 if I was at my desk all day and night.
I started with 24mg, then went to 18mg pretty quick for a couple weeks. I've been hanging around at 10mg since. I vape about 8ml a day, but I'm a very heavy vaper. You'll likey use around 5ml with a stronger juice. That's typical for a heavy smoker, but everyone is different. I've seen light smokers use 36mg and I've seen heavy smokers like myself use 10mg. It just depends on what works for you.
I think you'll find that once you get weaned off the analogs, you'll find it relatively easy to drop your nic. I vape 0mg on occasion and it does not result in any discomfort. Some people on the forum here claim that nicotine is no worse than caffine once you are no longer dependant on the other chemicals they put in cigs. Some are are addictive in themselves and others they add to enhance the effect of nicotine. I totally agree with that based on what I've experienced.
The big hurdle is the first few weeks. After that, you can comfortably give up the nic. Though, it may be hard to quit vaping because it satisifies the smoking experience. That's something a smoker never fully parts from. Personally, I have zero problem with vaping the rest of my life. It may not be perfectly harmless, but it's orders of magnitude safer than smoking.