Y.B.
I nursed my daughter till she was 2 and a half years old. I don't personaly see the need to supplement the breast milk. You said you put regular powder in your breast milk? I think that maybe you should mix the powder with water and then mix it with your milk if you must. Just my opinion. I used to put a little rice cereal but only to fill her stomach up and have her sleep longer. The weaning for me didn't work and everyone always had an opinion and the one that worked was "She stop when she is ready" and one day she just stopped. Good luck!
Y.