You might notice a slight dip around ovulation and/or the first day or so of your period. You might not. I have a friend who got her period back at about 8 weeks. She's still breastfeeding her 18-month-old. :)
If you do notice a slight dip, don't worry. Breast milk is supply and demand. Let your daughter nurse whenever she wants to. Drink plenty of fluids, and eat a healthy diet. Everything will be fine!
Like Jen said, you may notice it dip a bit right around the start of your period, but it will come back up within a day or two. I always encourage my little one to nurse a bit more often during that day or two and I've never had a problem. Also, don't be surprised if your period isn't regular right away. It's common for them to be irregular or sometimes to skip a month all together while breastfeeding. It's great you've decided to breastfeed for so long! My son is 13 months and still nursing and I've had my period back for 5 months now. Good luck!