You can't really go by how you feel coming out of the test. When I got done with mine, I felt like I had just been asked to translate texts from the language of an alien civilization that I had never seen before. I felt like I was guessing on most questions. However, I ended up performing almost exactly the same as I did on my AAMC full lengths. Your mind has ways of playing tricks on you after the fact while you're waiting.
What you're feeling is normal. I was always the kind of test taker who could guess how well I had done on a test pretty closely to the actual result. I walked out of the MCAT thinking 508 at best and ended up getting a lot higher than that, and significantly higher than my FLs. In the month that followed, I read EVERY thread about post MCAT feelings, and everyone seems to think they did awful, and usually end up doing around their FL performance.
Just remember, if you thought it was hard, a lot of people probably did. Ultimately your score is based on how well you did compared to everyone else.
Good luck OP and try to embrace the waiting game! It's a long month though.
Just took mine today, it felt so hard. I nearly voided because of the CP section, I almost ran out of time. No idea what was going on. I regathered myself during the break, ate my clif bar, zoned in, and managed to regain my form for the last 3 sections.
I decided to get it scored anyways because I felt like I would have wasted 7 hours otherwise.
I wish the AAMC would allow us to choose the order of the sections. It's computerized, so it shouldn't be hard to program. Taking that into consideration for the scoring would probably be a nightmare though.