I can have that problem, too. In my case, it's hard to keep steady pressure on the cutter if you can't walk around the table, and is your floor flat? I have the top of an extremely expensive cherry executive desk for the table. You can stand on it, no wiggles. But there is a slight dip in one spot, and cutter will miss there. My kitchen floor is vinyl over cement, and there are dips in that floor. You can see the puddles when you wash it.
I use either a True Cut or Martelli ergonomic cutter and have a Martelli mat.