Go short or not go short?

I picked up surfing a couple of months ago (at an age of 43). Found it's the most difficult sport I've ever tried, and the most fun one of course. I really wanted to improve but was so frustrated during my outings because making any little progress seemed so hard! Anyway, today I discovered the forum and also the "later starter" post! After reading that post, I felt so much better now
: like feel 20 years younger and no longer have the "lousiest surf learner" feeling any more.
Anyway, when I started in this January, I spent a few weeks in white wash and after a lot of frustrated sessions, finally can pop up most of time. Then I moved on to green waves. After 5 or 6 totally clueless sessions, this week I managed to caught a few green ones in a session and cruise along the face (each time just 10 to 20metres maximum because I took off a bit far from the peak I guess). I did this by angled take off and if I did a late take off or straight take off, I found it's impossible to do the bottom turn and go back to the face. This was mostly due to lack of skills of course but I am wondering if my board can be blamed too. It's a 7S Superfish II, 7'3", 53 litres. And I'm 5'7" tall and weighted 150 lbs. The 7S served me well in white washes but do you guys think it's too big and too floaty now? I did feel its clumsy when I tried to turn it, even in white washes. Again, my techniques were the main reason I suppose. But will it help if I can use something a little shorter? My goal is to be able to do top and bottom turns, reentry and cutbacks this year (if I'm not day dreaming)! I have to admit that if I go a bit shorter I may not catch any wave for sometime again.
Btw, I got a Bourton Shape's Fat Bullet 6'2, about 38 litres I guess. But it seems so short compares to my 7S and I dear not to try it now.

Anyway, when I started in this January, I spent a few weeks in white wash and after a lot of frustrated sessions, finally can pop up most of time. Then I moved on to green waves. After 5 or 6 totally clueless sessions, this week I managed to caught a few green ones in a session and cruise along the face (each time just 10 to 20metres maximum because I took off a bit far from the peak I guess). I did this by angled take off and if I did a late take off or straight take off, I found it's impossible to do the bottom turn and go back to the face. This was mostly due to lack of skills of course but I am wondering if my board can be blamed too. It's a 7S Superfish II, 7'3", 53 litres. And I'm 5'7" tall and weighted 150 lbs. The 7S served me well in white washes but do you guys think it's too big and too floaty now? I did feel its clumsy when I tried to turn it, even in white washes. Again, my techniques were the main reason I suppose. But will it help if I can use something a little shorter? My goal is to be able to do top and bottom turns, reentry and cutbacks this year (if I'm not day dreaming)! I have to admit that if I go a bit shorter I may not catch any wave for sometime again.
Btw, I got a Bourton Shape's Fat Bullet 6'2, about 38 litres I guess. But it seems so short compares to my 7S and I dear not to try it now.