Diehard
In Remembrance
I believe you when you say, "The toilet upstairs barely has any water in it at all, its like it is almost empty". It just doesn't compute.
Myself, I think I'd pull the toilet, carefully set it in the tub, on a rubber mat, and fill it with water again.
If it doesn't fill to a reasonable level, I'd start looking for a leak.
Some of the toilet models actually tell you the water surface area.
It's a mystery!
But the fact that there are somewhat similar problems with 3 toilets is too coincidental not to think there must be something common to all 3.
I sure hope you eventually find the problem. My curiosity is killing me.
Myself, I think I'd pull the toilet, carefully set it in the tub, on a rubber mat, and fill it with water again.
If it doesn't fill to a reasonable level, I'd start looking for a leak.
Some of the toilet models actually tell you the water surface area.
It's a mystery!
But the fact that there are somewhat similar problems with 3 toilets is too coincidental not to think there must be something common to all 3.
I sure hope you eventually find the problem. My curiosity is killing me.