There may have been points where I dropped a piece or something, but just didn't notice. I didn't really have any 'oh wait I just blundered something' moments.
7. Qd4 wasn't very good, I think 7. ...Qe7 was the right response, after 8. ...Bc5, 9. Qd3 my light square bishop was stuck (8. f3 didn't help for that). 12. xd5 probably wasn't great either, after ...Be6 you could take it back without problems.
It's not really any specific move you should have made at that point, just a feeling that you were doing better, trading off the knights and bishops was probably a bad idea.