S.B.
I don't have a lot of advice as to a weaning "pattern".
My first baby self-weaned well before a year old, and I had to go cold turkey with my second baby due to health problems. I simply could no longer put off having a hysterectomy and prior to the procedure, I had to have some injections that could harm my baby if I continued to nurse. After that first shot, there was no turning back. It was difficult, but I knew that caving in was not an option. Also, I was going to be in the hospital for a week so my son was just going to have to get used to a different routine. He was very much in love with the boobie, so I couldn't even give him a bottle because he would try to lift my shirt up.
The good news is, by the time I got home from the hospital, it was all over and he was no worse for wear. My husband was ready for a vacation and some sedatives, but the kid was fine.
Some moms have success with gradually reducing. Perhaps you could try a bottle of half breast milk and half formula just to see if you can get her used to it.
You've done a great job breast feeding for 6 months. I want you to know that it's not only okay, but very important for you to take care of yourself as well. Depression is nothing to mess around with, honey. I know you want to put your baby's needs first, and that's to be commended, but I tell lots of women that a happy and healthy mom equals a happy and healthy kid.
I'm sure there are some wonderful women here who will have some tips for you. In my case, cold turkey worked out best. I was given less than a week to get prepared and my baby did just fine in the long run. AND, I felt so great after my hysterectomy, it changed my life. I was like a whole new person. I had energy, I could travel and be physically active with my kids.
If I'd had a choice, I would have nursed my son longer, but I didn't have a choice. Looking back, I'm kind of glad it wasn't a long and drawn out process. It was what it had to be.
Remember....you have to be good to yourself too, Mama.
Best wishes.