it looks like you started to do it correctly, you have joined all the individual cells together fine with just the single nickel strip. But then you just connected them all together into one big cell…
But (If you were doing it in several cell series) the connection between the series is not enough, assume that each cell can deliver 15 amps, that means that all the cells together can deliver 105 amps (15 amps x 7 cells). So the strip at the first arrow will have to be able to handle 105 amps of current.
the connection between your second and third series is only 2 nickel strips, that means that together the two strips will need to handle 105 amps.
The connection between your third and fourth series looks to be only a single strip as well, once again it will need to carry 105 amps.
you have your individual cell series welded together fine, but what is really important is the connection between the series. I see a lot of packs on here being built with an 8 awg wire between packs, that will be able to support the 105 amps.
@L3chef listed some awesome threads to read up on. get to know your batteries as much as possible, you don’t need a fire to take away all your hard work!
Check out @Eboosted https://www.electric-skateboard.builders/t/eboosted-enclosures-thread/38073/772?u=skifree for just one example of a build.