First Auto Grow

Third week of flower, she got very yellow. Im new to this so I'm sure I made a few mistakes. From what I've researched it seems to be a nitrogen deficiency. I'm thinking its nute locked. So I flushed until the ppm coming out was what I was putting in, and gave it a few days. Then I fed with nutes the next watering. I honestly dont know if I did anything correct but she seems to be a bit greener today. Buds are definitely developing. Its so full, just need to make it a little longer now. Any pointers in the right direction on the yellowing would be much appreciated. Thank you for taking the time to visit my grow!