We don't know the height of Bulbasaur on four legs, only GameFreak knows what it's height is on four legs.
And, no it is not a lie, GameFreak made the Pokemon and it's height, so Bulbasaur's height is really 2 feet and 4 inches (0.71 meters).
There are actually quite a few Pokemon sizes that are nonsense. Take for example, Dunsparce. You just thought of a cute little 2 or so foot long snake right? Nope!! Dunsparce is actually 4 feet 11 inches (1.50 meters). That's huge for a snake that everybody thought was so small, its as tall as a Noivern!
But, that is the correct height for Bulbasaur because GameFreak made it, so it is how Gamefreak wanted it.
As for your models, in my opinion, you should make the Bulbasaur a couple of inches shorter than Squirtle. (But that's just my opinion.)
Hope I helped!