I would wait and see how essential a backyard is going to be for you.
If you don't spend much time at home (say, you both work, are busy on weekends etc) then I don't think it's a massive problem to not have much of a backyard. You also may find you have a child that's more interested in indoor play. DD is much more likely to be found reading a book inside than playing outside. It's just the kid she is.
If you have a local playground nearby, there's another reason why a backyard might not be that important.
I'd just wait a while... and then think about it and how important it is. I was happy when we got our house with a big backyard - but it honestly doesn't even really get used.