Board transition for beginner

Hi guys,
I'm new to the forum although I've been stalking the forum for a while
. I started surfing in July and I surf once a week (2-4hrs depend on my grumpy girlfriend). I use a 8' wavestorm board. Our beach breaks usually 1-3ft. I can catch most of the small waves. I keep getting nose dive or flip off the board if the wave is breaking too fast. One more problem I have is I can easily slip off the board while paddling (I can balance it with my 2 feet wrap the rail of the tail, but my feet would touch the water and it's not effective paddling). It doesnot happen if I wear wetsuit though, only when I wear rashguard. I'm practicing turning and angling the board while catching wave. Any tip would be appreciated.
I'm thinking about buying a 6’10" x 21 5/8" x 2 5/8" ($420) or 7'2" x 21 3/4" x 2 5/8" ($440) epoxy funboard for my first transition. According to the guide, 6'10 should be ok for me but according to the suggestions I read here 7'2 or 7'6 would be the choice. So i'm a little confused. I'm 24, 5'7 148lbs male. Is this gap too high? is $420-440 ok for the price?
Thanks all in advance
I'm new to the forum although I've been stalking the forum for a while

I'm thinking about buying a 6’10" x 21 5/8" x 2 5/8" ($420) or 7'2" x 21 3/4" x 2 5/8" ($440) epoxy funboard for my first transition. According to the guide, 6'10 should be ok for me but according to the suggestions I read here 7'2 or 7'6 would be the choice. So i'm a little confused. I'm 24, 5'7 148lbs male. Is this gap too high? is $420-440 ok for the price?
Thanks all in advance