Sure, ISP works, though I have seen people say either one for you. Anyway, lots of people call me an ISTP, and a lot of that is based upon my adventurous and explorative nature. I guess an F is more moderate and peaceful, whereas a T is more extreme and tenacious. In my opinion, you fit the ISFP description better than the ISTP description. Enneagram 9w8 also works, since you seem fairly free-spirited and like to just go with the flow. ISTPs would focus the flow.