Along with taking her off solids, you want to make sure your daughter is getting plenty of exercise, otherwise her poops are just sitting there and not moving along through her intestines, hence, the constipation.
At 6.5 months I don't know if she is crawling, scooting, rolling over and over, etc., to get to places she wants to go, but you have to encourage her to do so. Put her on her tummy on the ground, place toys 5 or so feet away from her where she can see them, to entice her to try and reach them. Once she starts moving place them a little farther away so she still has the incentive to move. Also sit on the floor sometimes about 5 or 6 feet away to try and get her to move towards you, moving a little as she gets closer so she'll keep moving. Help her exercise in 20-30 minute intervals several times a day.
Get her to like drinking water, too, as this will be very important in keeping her regular as well.
My guy was like your daughter at this age, and I have to tell you, he still tends to constipate at almost 3, lots of physical exercise is a daily must in keeping him regular, so be prepared to stay on top of this. Poop potty training was so fun....:-/