Feeling agitated, restless, with a million thoughts in my head felt like anxiety.
The difference is that mania is mainly not a negative feeling. Highly elevated, but glamorous! And the million thoughts fly like moths to a flame, not like panicky future scenarios. Sleep also eludes you, but you feel like you need to do a million things to consume all that energy. I guess you cannot sleep because you are high, not worried.
Somehow you might long for a dose of lithium, but somehow you also want to post-pone it.
It was actually mania. Interesting!