I think your lumens are a little off, but I think you should first consider the type of cfl you're using. You need to make sure that the cfl will help in both veg and flowering, so you need to first look at the kelvins. The general rule of thumb is that a 6500K is for veg and a 2700K is for flowering. The difference has to due with the light spectrums that they put out.
You would probably need a daylight/bright white for veg and a warm white for flowering. Even though it's an autoflower, it uses certain spectrums for certain parts of its life. The advantage of an auto is that the amount of light it gets is irrelevant. The auto will start to flower when its genetics say so. But if you want to get the most and not just a joint's worth, you need to feed it the right light during it's life...the sun doesn't have this problem, cause it has all the spectrums
You'll probably have to change the lights during the grow, which won't be that bad, but you should start out with the bright white for the veg..you'll see when she decides to start flowering and at that point, you could change to the warm whites...remember that the more lights the better...you could make a reflector hood out of a disposable aluminum pan if needed, but the more you can reflect the light the better.
Or, if it seems too complicated, then look for an agro bulb which has all of the spectrums (more blue for the flowering that red for the growth). I find they work best on autos and I am using one at the moment for two autos...it's a 200w bulb 2100K which puts out about 10300 lumen. I use it in both phases and it works well...
Obviously hps and mh will yield more but for an economical grow cfls are the way to go...
I hope this helps and sorry for being so long winded!!!
