I think probably because she has started taking solids that's why the frequency of latching has decreased. What you can do is to latch her more often as supply=demand, in order to increase your breastmilk supply. This is possible as I have low milk supply during the first 4 months (through pumping) and after I managed to train my boy to latch from breasts, my milk supply increased by double.
In addition, you can consider to do power pumping to increase your supply apart from direct latching. You can read up more from here on how to do power-pumping http://kellymom.com/hot-topics/pumping_decrease/
Please do not feel guilty for not able to breastfeed as long as you wish. I believe all mother wants the best for their children. But stressing yourself too much is not good for long term.
Read more