Congrats on choosing orthopedics! It is the best field, and I believe many of my colleagues will agree with me on that!
My biggest advice to you is that the end of the day, you need to do what you love. Please do not be so hesitant to apply into orthopedics because you feel that you are not competitive enough. If this is what you want to do, you should go for it.
I decided late in the game as well - probably around this time last year too. Although you did not go into medical school knowing you want to do orthopedics (like most applicants), I think it can show that you had an open mind during your third year and truly chose what you thought would be the best fit for you after experiencing it clinically on a rotation. So what I am saying is that it is never too late!
I agree that you probably need to get onto an orthopedic research project. However, I was in your shoes as well in that I did not have any ortho research and several posters in pediatrics. Even though I eventually found an ortho project, most of my interviews asked me to speak about my pediatric research because they saw that my project in pediatrics was more fruitful and could be discussed in detail. If your pediatric research was more hand-wavy, that will be hard to swing. I would definitely try to find an orthopedic mentor who can look at your application to advise you further.
In my opinion, your Step 1 score is really high. Unless you think you can do better than that, it will only hurt you to take Step 2 early. I took Step 2 early, but my score was not nearly as high as yours.
One of the most important things that programs look at is AOA. If you are still in the running for it, try to honor the rest of your 3rd year to get it. It is worth it!
When you go on sub-I's, crush them! Do whatever you can do to be the best and most helpful sub-I on your team. Prove to them how great of a resident you will be and how dedicated you are to becoming an orthopedic surgeon. If you can get letters showing that you did great at an away, it will truly help you.
Feel free to message me if you wish to talk further! Best of luck!