Starting Tomato Seeds indoors...when?

I live in NC and I want to start my tomato seeds indoors. Is it too late? And how do I make them plentiful when they start producing fruit? Last year, out of 9 plants, I got 6 tomatoes. I used high quality soil, seed starter, you name it. I fertilized, watered, and put them where the get 6+ hrs of sun a day and even used the soil testing kits. I have a green thumb with everything else but tomatoes. The seeds I start end up wilting and break off, so I end up buying the plants anyway. But I can cut off a stem and reroot it in water and have had the stem bloom indoors, and replant it early spring and have better results, BUT, no plants are to be found to do this, but I do have seeds, so I need help. Thanks.