No turning back

If what I'm getting is not what I want, should I say something and take the risk of losing everything? What I have is far from perfect, but it is still good and probably better than nothing. Ideally, I would be able to say it and then there would be two options: it would get better and closer to what I would like to have; or it would stay as it is and I would have to accept that's the best I can have. But the third and inconvenient option is that bringing it up would ruin everything. And there would be no turning back.