Do you hear any noise w/ using washer fluid? If not the pump, and a new one is cheap, or your lines are clogged.
A preliminary heater core failure may not fog the windows. You maybe have 6-12 months before it will. I put my core replacement off for one year when I frist noticed it.... but the fumes are toxic... if you have kids you should do it soon.
Current
2008 M5 6 Spd
2000 Z3 2.8 5 Spd MSport
2012 X5 35d Sport
1995 540i 6 Spd
1992 535i 5 Spd
Former
1995 530iA
1986 635CSI 5 Spd
2011 X3 2.8 MSport