My baby is constipated....?

She is 10 days old I feed, but i also supplement with formula, b/c she won't latch to my nipple and I am still not producing enough milk yet. I use infamil Soy based powdered formula, Her poop is not runny at all. its soft, but solid and lumpy, she has difficult pooping she grunts and I can tell she's trying to push it out cause she tenses up, and this goes on for a while then she has apoopy diaper, I know this question is kind of hard to answer, i am just worried....