I am worried my 5 month old baby girl hasn't had a bowl movement in 7 days is this normal? By the way she only breastfed.

Possibly! This may be normal--breast milk is such a wonderful food for babies that most of it gets absorbed at this age, leaving little to make into bm's. If she's not in pain and her last bm was soft, you can wait another 1-2 days. If she had a hard bm last time or if she seems to be in pain, please call her doctor.
Constipated infant . With breastfed babies the norm for bowel movements can be from multiple times per day to twice a week. No bowel mvmt in 7 days is a concern. You can give her 2 oz of prune juice mixed with 2oz water daily until she has a bowel movement. After starting cereals at 5 mo they can get slightly constipated, once she starts eating more of the stage 1 fruits and veggies her bm will become soft again.