BTW, what I did learn and could do was a left single and double with single handed rod, how slick
Well then that 11' 9" should not be a problem to learn on. If you are only fishing two handed a couple times a year the investment may not be worth it. That is a very nice stick and a 14 9wt will feel like overkill on skinnier water you will encounter as summer goes on.
It is a little easier to learn with a longer rod but not necessary. What line did you have on it? More often than not that is the issue. Sounds like you got most of the casts down and casting with your non-dominant hand on top is tough for anyone and takes a fair amount of practice no matter what rod you use. Did you try casting back handed, ie keeping your left hand up and doing a single across your body? For some this is the answer to having trouble with their non-dominant hand up top and is a perfectly acceptable way to cast.
Spey casting takes a while to get proficient at. It is truly a discipline and do not expect much your first year.
That being said there are lots of nice 14' sticks out there. Really are few if any that suck. I have not cast a bad one in a long time.
For bang for your buck look at the 12' 9" Echo 2. Not 14' but longer than you have...This is a great casting rod and doubles as a overhead rod. You get two tips and at $350 I think it is one of the best rods going. TFO also makes a good 14' 9wt for short money.
But if you got more to spend let us know. There are a lot to choose from. Just let us know how far you expect to cast, size of fish and the belly length of the line you think you are going to be comfortable fishing. Most beginners use short bellies and if that is the case you probably do not need 14' of rod to get the job done.