board question..girl needs HELP!

hey guys,,i posted b 4 when i was still riding my husbands 137 fluid, right now i am demo-ing a hyperlite, juvi 131. till my essence comes in. the problem i am having is , and maybe this is just "how it is"..i feel like if i am not constantly edging, the board is sliding all around under my feet, like i have absolutely no control. it is definately different riding this smaller board, on the 137 getting up was like piece of cake, this takes a little more "butt on the water before i stand up" work.. i am a female who weighs 102 - 104 pounds..4'11" tall and have ridden a total of 5 times. I guess my question is this : is this normal for this size board? is it just going to take some getting used to since i was riding on a board that had so much larger surface area?? has anyone else experienced this "glassy sliding on the water fish-tailing"??? please any input would be appreciated..because i can still demo a bigger board if need be..i have not purchased it yet, just the bindings. oh and by the way, the 131 is much better for my carving and i can get way more air...but just the sliding riding is bothering me...??? what gives?
help a girl out.