There is a big two-way correlation between bipolar and drinking - more drinking among bipolar and more bipolar among drinkers. You know you should mention this to your therapist but are withholding it. This may not be your fault - maybe the therapist does not elicit straightforward honesty from you and maybe you need a new therapist. It is hard to advise - we know that in Canada and UK the options are much more limited, but it seems that there is a clear positive datapoint in the past in that you had a psychiatrist who helped with GAD - who diagnosed correctly and treated effectively. Why not go back to that psychiatrist?

Also, I think you are mistaking a well-contained manageable elevated state for normal state when you write that when you feel "I'm full of new ideas, new projects, I'm enthusiastic, excited and feel like the future holds great things for me. I'm self confident, decisive, rational, intelligent, practical.", you feel just like normal people do. Normal people do not consistently feel full of new ideas - the world would not be what it is if they did.