same thing that would happen to you if you only ate only toast for an extened period of time...eventually youre going to get hungry, then sick. And if you dont feed properly when flowering, you may be very dissapointed if your plant makes it.
If you need to buy time to work out a proper feeding schedual than go pick up some Grow Big; it's 6-4-4 compared to BB's .01-.3-.7. (use together)
This will allow you to continue vegging w/ a great food source while you save up for the rest or maybe ask some of the peeps around here for some cheaper homemade recipes...that will work just as well.
BB is good stuff and is designed to improve the plants nature resistance to the dark side of the force (sickness, bugs), but will not keep her going alone forever.