A GA Pilot on base leg reported a NMAC with an aircraft on the final approach course.

Narrative

Was participating in an event at ZZZ. Pattern was much busier than normal and Tower was issuing rapid fire instructions to aircraft in the pattern and approaching the D. I was flying a right downwind for Runway XX and was told I was number 2 in the sequence behind a Skyhawk. I identified the traffic to follow and began my turn to base shortly after. Upon turning on to a base leg; I saw another aircraft on final. I believe the tail number began with XX and the tail was narrow like a Diamond type; though I am not certain at all.The tail was directly in front of me; so I turned away from final to a 224 heading away from the runway. My first transmission was to report that we had gotten quite close to the other traffic and that I had broken out of the sequence. The Controller came back in an exasperated tone and said they had instructed me to follow the Skyhawk. I didn't respond right away; but then told the Controller I was on a 224 heading and I was fine if I needed to go back to the beginning of the pattern to re-enter the sequence. The Controller indicated I should continue flying westbound and standby for further instructions. Shortly after the Controller asked me if I had visual contact with a helicopter and I reported negative contact. I was still headed away from the airport and did not have them in sight behind me. The Controller told me to turn in and the remainder of the approach to landing was completed without incident.I don't recall anyone in the pattern being asked to visually identify other aircraft prior to my conflict with the other aircraft on final. The traffic I believed I was following was issued a landing clearing shortly before I turned on to base. I suspect the third aircraft in the sequence turned in before I did from the opposing base. For my own part; I was definitely concerned with the amount of traffic in the pattern as it was far beyond what I had experienced in the 18 months prior while flying at this airport. I also had a youthful passenger as a part of the [event]. I have flown this type of mission previously and I didn't feel particularly stressed about that piece; but it is unusual for me to fly with a passenger. I was well rested and ready for this flight. I also felt like I had a good idea of the sequence I was to follow; but I could be incorrect about specifically being assigned #2. I don't think that is the case; but I acknowledge it's possible.