Hello David,
I understand it is a hard time to you for deciding your future because I was there as well (actually, everyone has had their own as well). I am sure that you will find your suitable path.
It is sweet that you provided your suggestion of being truly happy. Actually, I agree with what you said that "very few people are truyly happy". The coincidence is that I thought of how to be truly happy last year because I suffered from a sorrowful event then. This sorrowful event has completely changed my life (I shall say my thinking). When I was drowned in the sadness, it was unintentional to search the Dalai Lama's book you recommended above and I only read the sample pages of it from Amazon/Google. I had realised something before I read these few sample pages in his book. Since you remind me of this book, I shall read it in detail when I am in the bookstore next time.
Finally, take care of yourself. I personally think if we can take care of ourselves well, we can, as well, take care of the people we love. Health is very very and very important.
Best wishes,
xiao_xiang113