When you say you grow tomatoes indoors, how do you do that, exactly?
I put them in a container of potting mix. Set them in front of the sliding glass door that faces south west. When the sun sets, I turn on a grow light - full spectrum bulb until 8pm.
I use the grow light instead of the overhead lights for room lighting. They grow slower and a bit smaller than outdoors. I also give them a half dose of fertilizer once a month, since the pots are smaller than optimal.