Hard situation, you’re going to get the every response in the world from, every type of mother. The breast feed till there 5 group and the weaned at 3 mos to go back to work group. Ultimately, the decision is yours. I have three kids, the first two weaned them-selves. My eldest at 9mos, so we had to supplement with formula, and my second weaned herself at 15 mos; but, I had found out I was pregnant w/ number three about that time, so I thing that had a lot to do with her weaning herself. Plus I told her they " my breasts where broken and put band-aids over my nipples" she said ok and that was it, she really never asked about it again.
At 13 mos you really can’t reason with a baby. But, you also need to feel like your comfortable nursing, the last thing you should do is continue to nurse at the expense of your sanity. It will compromise your feelings towards your baby. Working full time and nursing is exhausting, I’ve done it I know. Commuting, getting them to daycare picking them up… then dinner and trying to nurse an over 20 pound kiddo is not easy. Plus the expenditure of energy it takes for your body to produce breast milk.
You can wean her in about a week, I would take away a feeding a day or maybe every other day. If you’ve gone back to work already than she is likely already not getting the daytime feedings.
I feel for you, I have a 19mo son who shows no signs of being interested in weaning; I’m going to wait till he’s closer to 2 so I can explain it to him easier. I should have done it at 13 mos. GOOD LUCK!