DD is 9 mths, 20 lbs.
Have you ever tried nursing on one side while pumping the other? This obviously will not help when you return to work, but I usually find I letdown easier for the pump when I'm nursing on the other side. Maybe if you can train your body to letdown for the pump in this way, it will be more conditioned to do so even w/o baby. Just a thought.
At 9 mos old, I'd say you could definitely add a second meal of solid foods (I wouldn't worry about purees, necessarily - just give baby some soft cooked table foods and let her eat what she'd like).
At 9 mos there is a pretty good growth spurt, so I'm not surprised you're feeling baby is wanting to eat more right now. Personally, I don't think you need or should use formula. Baby's behavior is not an indicator of a need for more milk, assuming that baby is having adequate diaper output and weight gain on breastmilk alone. Teething is a big issue at 9 mos that frequently makes baby more wakeful at night, and my own children wanted to nurse a LOT more during teething times, as well as times they were working on developmental milestones. It doesn't mean you don't have enough milk. It typically means baby is wanting more snuggle time or the soothing relief of sucking / nursing. By using formula, you're more likely to damage your milk supply. Now if baby is not gaining or having adequate wet diapers, formula might be needed, but I'd also work on relaxing for the pump so that you can try to pump more.
When you return to work if you are unable to letdown for the pump, you can consider partial weaning or combo feeding, which is when moms use formula during the day and then nurse exclusively at home in the mornings, evenings, nights and all weekend.
I agree it might be time to increase some solids. Another strategy if you aren’t going to pump is to have day care give all the solids and focus more on breastfeeding when you and baby are together.
Kathy Kuhn IBCLC ivillage lactation consultant Grammy to Brennan, Elias, Elianna, Tahlia, Makenna, Maura, Silas, and Charlotte