As Paul says, 1 and 3 are both correct and common, and 1 would be the usual way of saying it in the US. 2 is incorrect, but can be made correct if changed to "I used not to drink coffee". I think that's not common in the US, but is heard in the UK. There is also "I used to not drink coffee", which to me sounds awkward and perhaps even incorrect, but people do say it.