I dunno if you can actually overfeed a VFT. I have on many occasions seen my plants with zero open traps at all. They always just chug right along.
Its summer in NZ right now so if its at all possible I suggest you put your plant outdoors and let it catch its own food. VFTs can tolerate temps anywhere from about 0c to about 42-45c and extremely low humidity. Keeping them outside will also allow them to enter dormancy on their own and now is the time to start thinking how you are going to handle dormancy for your plants.