Think of it like this. If you've got a normal sized plant, it will take up a more than .1 sq. ft. when it's harvested. That means you should have at least 5000 lumens per finished plant. You can use less when you're vegging, because the plants don't take up as much room. And, of course, you'll probably lose one or two that are male. But if you're planning on finishing 2 or 3 plants, you're going to need at least 10,000 lumens; 15,000 would be better. 20,000 would be better yet. You may be able to use less light now because your plants are small, but you'll need more later.

Watts have nothing to do with light. Watts are a measure of the energy used to light whatever bulb you have. So don't use watts. Lumens aren't a perfect measure, but they're the easiest way to tell if you've got enough light. Whether it's with more bulbs or higher output bulbs, try to get more light. Good luck!