Happiness is very elusive for me, as well. I have discovered yoga. Although, a lot of people treat yoga as a form of exercise, the true purpose is to gain clarity. Using the mind, body and breath, it is possible to calm the mind of intrusive thoughts to see your life in a different light.
For me, I spent over 50 years with depression and hating myself from repressing the fact that I was TG. Obviously, I was never happy for almost my entire life. Then I accepted that I wanted to be a woman and realized that if I transitioned or even made myself more feminine e.g. crossdressing and shaving my body, my marriage would be over. I would also lose most of my community of friends and possibly family members. So depression was replaced by gender dysphoria. Once again, I was not happy.
Finally, I gained clarity and stopped pressuring myself to be happy. Instead, I started to look outside myself for all of the good things I have ~ a loving wife and children, good friends, the beauty of nature, wonderful music and dance. I changed my focus from myself to others and found contentment in giving of myself to make people in my life happy. If I couldn't be happy, at least I could gain some gratification from contributing to their happiness. I still hate myself, I still have gender dysphoria, I can't say I am happy, but I can live with being content.
I hope that helps.