stuntnun the biological weaning age of the human is estimated to be 3-7 years. Feeding to 2 1/2 is very common and is absolutely for the mother - continuing to breastfeed continues to reduce her chances of breast and ovarian cancer and osteoporosis. This is on a dose basis, ie the longer she feeds for, the more protection she gets.
On the other hand is it just for the mother? Have you ever tried to breastfeed a child that doesn't want to? That's just not possible. Children who breastfeed for longer than other people expect continue to want to breastfeed.
A child's immune system does not mature until they are around 6 years old. The antibodies in breastmilk are designed to fill the gap between birth and the maturity of the child's own immune system. Furthermore breastmilk contains long chain fatty acids which are specifically designed to build human brains which is important throughout childhood. These cannot be replicated. These are just two reasons why the breastfeeding relationship doesn't have to stop when our society expects it to :)
voyage How you approach this really depends on your work schedule. For instance, if you work regular hours you can, if you want to, continue to breastfeed morning and night, and on weekends. At least you can cut down to just these feeds, giving you more time to transition without having to stop completely before you go back. If you work shifts then this might not be the best option, so just factor this into your choice of which to drop.
So say you're working normal hours, then yes, as you say, dropping the mid morning and afternoon feeds would be the best option to start with for most people in that situation. Ideally dropping one at a time, leaving about a week or more between a dropped feed, allows your body to adjust nicely without discomfort and minimising the risk of blocked ducts which can sometimes lead to mastitis. At 9 months her diet ideally should be around 50% breast or formula milk and 50% solids so I would be replacing those feeds with EBM if you can, or infant formula (not follow on). Not cow's milk.
9 months is a nice age to wean actually, if you're not planning to go for child-led weaning which as you say, in your position is not straightfoward. Generally a baby of 9 months is much easier to wean than an older child. So if you do find or decide that complete weaning is the best option then just continuing with the process of dropping one feed every 1-2 weeks should be relatively straightforward although you are more likely to have some difficulty with the bed time feed. Trying to do something different to her normal routine might help, especially in the morning. Having someone else around to do the night routine if this is possible can help. Lots of cuddles and love will help her to transition and at all times understanding her point of view, that she is having to reduce something that she loves, and trying to fill that gap with love.
It is absolutely normal to grieve the loss of breastfeeding and this can last for a while - and sometimes that sense of loss doesn't ever really go away completely, but feeling proud for the amazing gift that you have given to your daughter can be helpful. For instance, did you know that while reducing your risk of breast cancer you have also reduced your daughter's as well? Your little girl will still need you for a very, very long time and the ways that she needs you will change. You'll always be the person she turns to, and she will always love you. (Well, except for a few years when she's a teenager 
). Don't dismiss your feelings of loss. Accept them and talk about them to someone who understands - and know that you are very much a part of a huge community of women who completely understand how you are feeling about that aspect of being a parent.
And finally, don't forget that unless you want to you don't have to stop completely. It's fine to continue for as long as you both want to when you are together, if that is your choice. Your milk supply will adjust.