My daughter started sleeping through the night by 12 months, however I onbly stopped breatfeeding her 2 weeks before I got pregnant with this baby (15 months as well). I started dropping 1 feed at a time to start. So if she's used to falling asleep on the boob, that will be THE hardest one to get rid of, so that will be the last to go if that makes sense. I would drop one feed, and then a week later drop another feed and so on. STTN can be a hard one though. I really had to force it with my daughter (during the day). Not easy...but she now is weaned, and happy. Took a few weeks to be completely done. Best of luck!!! You will do great. Sometimes its harder on mom than it is on the child. She is waking out of habit, so figuring out what you're comfortable with regarding crying etc is what you'll have to figure out first, and then consistency is key.