I nursed my daughter until she self-weaned at about 2.5 years old.
During that time, I got pregnant once, but miscarried... not due to the breastfeeding though.
You can either (1) let her self wean, if you are not in a "rush" to get pregnant again (2) wean her, gently. You can distract her when she wants you...ie: get up and don't sit down... make yourself "busy." Tell her, "One moment, Mommy is busy now..." or get her distracted with an activity.... (3) explain to her that she is a "big girl" and "one day...." she will have to stop nursing. This is a gradual thing though. Not cold-turkey. (4) let her nurse ONLY at certain times of the day or night.... explaining to her. (6) give her some kind of substitute. For example... she must be drinking milk by now, right? Perhaps, give her that instead...
Yes, any nursing child may "appear" to be anxious about it all and want you 'available' to nurse. It's normal... because THIS is a transition for them... they are changing... .and you are changing. It's a natural progression.
I realize you are 41 years old... but if it is any consolation.. I was 42 when I was pregnant with my 2nd child. And everything was fine. Normal pregnancy. And my son was born normal and healthy.
Since you DO want to wean her & need to... you have to use distraction methods, as well as talking with her about it all. Gently. With any child, they will get "anxious" because it is a "change" for them. It's normal. For me, I talked with my daughter about it. I allowed her to self-wean... and she did. But I did talk to her about it... explaining that "one day" she will not be nursing... she will be a "big girl" etc. And one day... out of the blue... she just stopped. She told me simply "I'm a big girl Mommy.... I don't drink (from you) anymore..." and she even laughed and thought it was funny that she "used to" breastfeed! And that was that. The end.
At her age, even if she does get sick... you don't "have to" ramp up your breastfeeding. She can take kid vitamins. That is what I did.
The thing is using gentle talking with her about it and explaining it to her. Using distraction. Making yourself less 'available" to her. Wearing clothing that she can't just pull-up and grab to get to your boobs. Teaching her "manners" about it... ie: that YOU decide when is nursing time... that there is a time and a place to do it... that she try and do an activity first before nursing. AND CHANGE THE PLACE where you breastfeed (ie: not in bed. Perhaps do it just in a certain chair. And that's all). YOU decide where... .not letting her decide where. THEN... you LESSEN the amount of time that she is at your breast. Then pull her off.
Don't worry... they will adjust. It's a progression. A transition like anything else. In time, she will understand.
For you, don't make the nursing sessions 'emotional.' Don't bring attention to it. If she senses your anxiety, she will feel it too. Just make it a 'routine' like brushing your teeth.
If worse comes to worse... perhaps just use a "reward" chart or something... or telling her she can choose a special "prize/toy" when she stops breastfeeding. But the key thing is... she has to "understand" that breastfeeding will "END" one day... and there is no going back to it.
oh! One thing my friends did (with success), is they put band-aids on their breasts covering the nipples, and they told their child "Mommy has a bobo...." or "Mommy's milk doesn't work anymore.." and things like that. They said this worked for them.
All the best, just some ideas and what I went through.
Take care,
Susan