stopping breastfeeding

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I'm currently 10weeks pregnant and still breastfeeding my 15month old daughter. I thought I want to tandem breastfeed, but I don't think I'd be able to. I'm already so exhausted breastfeeding her and being pregnant. I can't imagine her getting jealous and trying to fight the baby for some milk. So I was thinking of weaning her off, but I'm not quite ready yet and I think neither is she. So I was thinking if there is a really slow and gentle way to stop? I wouldn't mind if it take 2-3 month to completely stop. Does anyone have any tricks? I already give her water at night, and she asks for it, but she also still asks for milk after she drank water. She only drinks at night. I stopped feeding her in the day time. She never slept through the night and probably won't until I wean her off.