Bless her heart, that's miserable. : ( I don't know if I would say it is "normal" but it is definitely common. Both of my boys have been formula fed--but the oldest was only constipated one time, and the baby has been constipated twice. I do think it is considered normal for a formula fed baby to have a day or so between dirty diapers--that all depends on what is already the norm for your little girl.
How old is she? (I'm assuming just a couple of weeks based on your ticker?) A warm bath sometimes helps, probably a little more so when it is accompanied by a belly massage. Then depending on age, you could try a little bit of diluted juice, and if she is REALLY having problems, my pediatrician recommends glycerin suppositories (I personally would use those as a last resort, but just because they sound horrible--I've never actually used them for my boys before.)
We (accidentally) fed my 8 month old several bottles of the wrong formula (long story lol) and he went 3 days without pooping. Poor guy would strain and push, and just not get any results. A couple of warm baths and a few ounces of juice finally did the trick for him!
I saw your post is a few days old, so hopefully you figured something out that worked for her and that she feels better
