YABU. My DD is the same age as yours, and spends 2 nights with her dad (not on consecutive nights) and 5 with me - although we will probably change that to 3/4 nights soon.
We have done this since she was nine months old. It was really hard at first, but has worked out brilliantly.
The fact that she spends a good chunk of the week with her dad means that they have a really close relationship. No way would this have happened if he was just visiting her, taking her out for the day, or having her every other weekend. He has really had to take responsibility for her, and has turned into a great dad.
We will need to review how our arrangement works when she starts school, but I don't see any reason why it shouldn't continue to work.
It works out well for us too - I have time off to work/socialise/have a break, and DD's dad gets the satisfaction of knowing that he is an equal parent, not just a visitor.
I know how painful it is to work these things out, but if you can make it work I do believe it's best for everyone.