Borntorave,
You don't need to take another test. I think there is some test out there that measures the levels of your cognitive functions so that you can see which preference order matches which type, but ultimately the best way to understand your MBTI type is through personally understanding the cognitive functions, and recognizing the preference order that your brain uses.
An excellent resource that compares the cognitive preferences side by side to make them make more sense is this link:
comparison of Jung's 8 types
Look up the wiki on ENFP and INFP and look at the order of the cognitive function preferences, and use the previous resource to understand what order you use. INFP's dominant is Fi, and ENFP's is Ne, as I mentioned in the last post. Read up on those, and see which matches your dominant function most, then see if the cognitive functions that follow match the order of the cognitive preferences that you use.