Sometimes lack of interest in solids can be a cue that your LO isn't ready yet, sometimes it just means that your LO is taking her time getting used to a new way of eating. It's okay to keep trying but if you or your LO seem to be getting frustrated, take some time off and come back to it again. Both my kids started solids at 6 mo and it took them several weeks to get even slightly interested. Even then, they both barely ate until they were old enough to start finger foods and BLW.
I wouldn't worry about it too much, just give it time. Like Laura said, breastmilk and formula have waaaaay more calories than solids, so you might increase milk if you're looking to increase weight gain. Solids can actually work against you, since they can decrease milk intake.