Please ease the frustration!

Hi guys,
I've been surfing on an 8' O'shea board since feb this year and have got to a level that I can ride down the face of a wave and put in a turn at the bottom going left or right. I have recently bought a 9'3" Tombstone longboard and I am struggling like hell. (I'm 6'2" and about 13 stone). It paddles out like a rocket, but when it comes to catching the wave it seems really slow, when I do catch a wave I pearl the front something rotten. So I have moved further back (so toes are in the water at the back of the board). When I do pop up it seems to just die and it feels really unstable (due to the fact it only has 1 fin and other board has 3) and I usually fall off.
Does anybody have any tips or suggestions as I went out for the first time in about 4 weeks due to extreme lack of surf and had the sh1ttest time I've ever had, while all the other longboarders where getting long rides
I've been surfing on an 8' O'shea board since feb this year and have got to a level that I can ride down the face of a wave and put in a turn at the bottom going left or right. I have recently bought a 9'3" Tombstone longboard and I am struggling like hell. (I'm 6'2" and about 13 stone). It paddles out like a rocket, but when it comes to catching the wave it seems really slow, when I do catch a wave I pearl the front something rotten. So I have moved further back (so toes are in the water at the back of the board). When I do pop up it seems to just die and it feels really unstable (due to the fact it only has 1 fin and other board has 3) and I usually fall off.
Does anybody have any tips or suggestions as I went out for the first time in about 4 weeks due to extreme lack of surf and had the sh1ttest time I've ever had, while all the other longboarders where getting long rides