Breastfeeding while pregnant

I'm currently 13 weeks and I am still nursing my 1 year old but I don't feel she is getting as much milk as before. My goal was to nurse her for a year & I am happy that we've made it this far. I just want some advice on how to wean her off the boob. She can be a picky eater and won't take a bottle. I have tried giving her organic toddler formula but she didn't like it. I wish I had the strength to continue but unfortunately I don't. Any tips help. Thanks.