Considering the nature of the poorly defined question, it is the short school bus. You know, the bus that is usually reserved for the special needs children. Plus, no school would waste money sending a 60+ person bus out to get only 7 girls. Thus, we can safely assume it is a type A1 bus.
Type A1 busses are limited to
10000 pounds gross vehicle weight. That is the weight of the bus + driver + passengers + all cargo. We can assume that we won't exceed this weight limitation since that would be breaking the local laws. Heck, the bus might not drive properly anyways. The typical A1 bus is 2-3 tons. So that gives ~5000 lbs for the passengers and their items.
Assume each backpack is 2 lbs, each adult cat is 10 lbs, each kitten is 2 lbs, and that the driver who picks up the girls is 150 lbs.
[*]Stop #1: The first "girl" is wearing 7 backpacks. In those 7 backpacks are a total of 49 large cats and 343 kittens. Thus, this "girl" is carrying 1190 lbs on her back. No "girl" can carry 1190 lbs. Instead, each "girl" is actually two adult male cross-dressing bodybuilders masquerading as a single girl. Total weight of two bodybuilders: 500 lbs.
Thus after picking up the first "girl" the bus has: driver (150 lbs), two crossdressing bodybuilders (500 lbs), and cat filled backpacks (1190 lbs). Total: 1840 lbs out of 5000 lbs available.
[*]Stop #2: same as #1. Pick up two more bodybuilders and the 7 backpacks of 392 cats. Total cargo weight is now: 150 + 2*(500 + 1190) = 3530.
[*]Stop #3: the bus cannot move once the third "girl" is on with her cats. She has to open several bags to remove excess weight, the cats run out of the bus like a bat out of hell.
[*]Stop #4-7: same thing. Each time to let on a "girl" (two crossdressing bodybuilding men) more cats must be released.
Now to move from here, the bus can only hold 5000 lbs. So, how many cats were removed? Depends on if they got rid of kittens or adults. No one likes the adults as much as they like kittens, so lets just say they got rid of all of the adults.
End result: 1 driver (150 lbs), 14 bodybuilders (3500 lbs), 14 backpacks (28 lbs), and 661 kittens (1322 lbs). The number of legs are thus: 2 + 28 + 2644 = 2656.