Take all the known stars put them into a sphere shape, How many light years the center to the edge?

There is no such thing as "the known universe". We don't know how many stars we can see or how big they are or how far apart they are. It's all guesses. Highly scientific guesses, of course, but still guesses.

If you look at something from two positions it appears to shift by some angle depending on how far away it is and the length of your baseline. If you look from opposite sides of the Earth's orbit, that is the longest baseline we have, and accurate measurements can be made out to about 3200 light years. Beyond that we are guessing. Highly scientific guessing, but guessing all the same. That is why when you try to look up the biggest stars, the figures get very uncertain beyond 3200 light years.

A big part of science is conjecture, which means making up "What if" scenarios. Often those scenarios get discussed a lot for a long time, and people begin to assume they are true just because they keep hearing them. The big bang is one such scenario. The big bang exists only in somebody's imagination. It was needed to explain implications of the expanding universe conjecture, which was needed to explain the receding galaxy conjecture, which was based on the observed red shift in light from galaxies and the assumption that the red shift is caused by the Doppler effect. If that assumption is wrong then the entire collection of conjectures is without support. There are other possible causes of red shift. Hospitals use a magnet to produce red shift. It is called MRI.

Science is supposed to be based on observations, tests, and proofs. There is a strong tendency to accept conjectures, math models, and consensus of opinions instead. You need to be careful about accepting things that have not actually been observed.