1- It wasn't enough time. Normal usage, neither formal nor informal. Only use this one if the topic (project, assignment, whatever it is that requires time) is already understood between both speakers. 2- I haven't enough time. Uncommon in American English, common (I believe) in British English. This would be considered kind of formal in American English, however if I were to use this, other Americans might think I am weird/pretentious. We would not think this about British speakers. 3- I don't have enough time. Normal, neither formal nor informal. 4- I hadn't enough time. Same as #2. Normal for British English, formal/awkward for American English. I would never say this. 5- I didn't have enough time. Normal, neither formal nor informal. Hope this helps