May have screwed up installing new cam. Need help!

Ill explain what I did to find TDC this time around for clarity.

I used a piston stop; the kind you screw into the spark plug hole. I had to screw it in almost to the bottom to get the piston to actually hit it. But I saw videos that stated it didn't matter how much you screw it in, just don't move it after you start.

I put a piece of tape on the damper, leaving a bit of the damper exposed for when I made my final mark.

I turned the engine clockwise till I hit the stop, then made a mark on the damper at the 0 mark on the timing mark.

I then turned the engine counter clockwise till I hit the stop. I made a mark on the damper at the same 0 mark I used as the reference point.

Finally, I turned the engine till the two marks I made were exposed on the driver's side, as this was the place where I could get my tape measure in and see what the measurement was. Thats why its on the drivers side in the picture. The measurement came out to 4 inches. Half of 4 is 2. So I made a mark at 2 inches on the tape and extended it to the damper. The mark ended up being close to the factory mark, but there seems to have been a bit of slippage over time.

Hope this helps clarify things!
That sounds right. Did you do it twice to verify the first results?