I want to feed my daughter to 18 months?

At 10 months of age, I wouldn't be restricting her feeds. milk is still (or should be) the basis of her diet. As well as three meals of solids, just demand feed her. There is no need to start weaning at 10 months particularly if you intend to feed her until 18 months. Another suggestion is to let your daughter self wean. When she is 18 months, you may very well decide to continue feeding and at 18 months your daughter would be very happy with just one or two feeds. I'm still breastfeeding my 20 month old and he's not ready to be weaned yet (despite that I would be only too happy if he stopped,lol). BTW you shouldn't feel any guilt for "only" breastfeeding your twins until 3 months. You didn't fail at breastfeeding them, you managed to breastfeed for 3 months which is something to feel proud off. I am also very sorry for the loss of your child. I wish you all the best. Good luck. Breastfeeding isn't easy so I commend you for intending to breastfeed until Holly is 18 months.