Testing Boundaries

My little girl is now in the stage where she is beginning to become more aggressive in doing things new to her. She is now cruising along furniture. She won't even stay inside her exersaucer. She preferred to be outside and cruising around it. If I pick her up she wants to go down and want me to hold her so she can walk. My back starting to get hurt everytime I stoop down. She is really testing her boundaries now how far she can go. Although I can sense that she is still afraid if she feel she cannot do it. She loves to play a lot now too and refuse to go to sleep even if she is very sleepy. I am very glad that she is doing well and very healthy even with the concern of her slow weight gain.