More light = Better!
I would get more light, also the flouros you have, what spectrum are they? You will want something in the 5000K range for veg and something in the 2000K range for flowering. Also if there is room in your budget, I would recommend upgrading to HID lighting. I have a 100W HPS that I run over a single plant and it is doing very well, for a total cost of about $50. I could easily do 2-3 plants under it. Another option is to add some CFL's if you can't/don't want to do HID. Adding a few CFL's can greatly help a small garden. If you are looking for the most cost effective route, I would add 4-8 CFL's depending on what you have room for. For CFL's its 6500K(Soft White) for veg and 2700K(Warm White) for flowering. Hope this helps.