I think it came to me as a bit of a surprise to be labelled, "extrovert." I'm not really outgoing with people, but I think I can see how I can be seen as one.
I'm not very reserved, but I do spend a lot of time alone. And I really like dark, enclosed environments. Like caves.
The reason I ask why you say you can't be an introvert is to see if your reasons relate to definitions that are not used in MBTI.
All the definitions about extroverts being loud, talkative, social etc and introverts being shy, quiet, reserved etc get in the way of understanding MBTI uses of the words. Forget them.
I've stated with conviction in the past that there was no way I could be an extrovert cause I couldn't get over the idea of being social and/or loud, all that did was keep me sure that I couldn't see myself in any Extrovert profile. After reading a lot of information on MBTI and Socionics EvI I realised, to my horror, that I am in fact ENTP
People who have no knowledge of MBTI would call me introverted and quiet and more of a listener than a talker, which is true, but according to MBTI my focus is external, my dominant function is Ne and when I go out and have a good time I have way more energy at the end of the night than I did at the start, whereas if I'm on my own too long I start feeling like I'm sinking in quicksand even though I enjoy being in my own company, it just doesn't energise me.
Maybe you're an introvert, maybe you're an extrovert, iunno, but how long you spend alone or with people won't tell you which you are, it's how you react to those environments that counts.
Recon I've linked
this in about a gazillion times cause it really helped me determine my preference, it's Socionics not MBTI but have a looksee in case it helps.