Yet i was also told, that to achieve jhana one must follow the tetrads. However i thought it was uneccessary to keep attention on whether the breath is short or long and other stuff like that.
Maybe the Jhanas aren't as complicated as they make out. The first two levels involve discursive thought which isn't hard to achieve! So, from what you have explained, you may well have been in one of them. Don't forget that the house of samadhi is built on Sila foundation and the purpose of it all is to allow panna not jhana to arise. We need to devote as much time to all aspects of practice. When jhana comes along you'll know.