I'm currently tandem nursing. I'm letting my girls self wean so unless I wanted a bigger age gap TN it was. Nursing is very important to my older girl. She nurses 3-4x a day for 10-20mins per time. The baby rarely spends that long at the breast

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When the baby came DD1 was used to nursing off both boobs so I had to limit her. I told her only one at a time so that I'd always have a full one for the baby. She objected a bit but is fine with it now. Sometimes I feel like my older girl might suck me dry (dont remember to drink enough and used to get headaches in the early days). If I dont feel like nursing her right away she is usually pretty OK with waiting. I usually only ask her to wait once, the next time I give it to her. Sometimes she seems to be trying to be exclusively breastfed, if she asks to nurse twice with not much time and no other food in between I tell her that she has to eat or drink first.
I dont regret letting my older daughter nurse through pregnancy and to tandem nurse now. Nursing has always been so important to her. Sometimes I wonder if she'll out nurse the baby.