Well, one thing, if your max range is only 90k for the meson, you can reduce size a little by building a fire control that comes a bit close to max range. Also, is that tracking speed 15k or really 1500?! because that's a HUGE difference, and one that will very likely bite you in the ass when your fighters can't hit the broad side of a barn.(remember that designating a beam fc fighter only automatically gives it a free 4x, so no size increase needed to track targets).
I wouldn't call a 15-20k carrier all that large really, and that's about the size design I usually end up with when designing a fighter of similar size(I usually have 1 strikegroup of 10 fighters, but you can have any size/number of strikegroups, as long as you are prepared to build a carrier to hold them all!)