I'm really sorry for what happened to you in your past.
I wonder whether what the doctor was trying, in a badly phrased way, to say, is around research that some people are naturally say a 7/10 on a happiness scale, and some people are naturally a 4/10. It isn't that you don't have the capacity for it, just that you might naturally tend to be at a particular point on the scale.
As someone who used to be about a 4 and is now typically about a 7, it was kind of true, and also I made changes and am generally much happier with my life now, so it's not immovable.
Anti-depressants don't typically "make you feel happy", but they can relieve the suffering sufficiently for you to make lifestyle changes and/or have the capacity to process the trauma in therapy, and those things can make you feel happy.
How long you need/want to be on them is very person-specific, and also there are many different ones, which each work for different people, so there might need to be some trial and error. There not a solution for everyone, but many people find them helpful, so I wouldn't write them off before even trying.
Making sure your SHED (sleep, hydration, exercise, diet) are all healthy is a good basis for beginning to shift mood, plus getting out in nature.
Obviously it's not a substitute for therapy, but if you can't afford to go private, then there are charities which provide free counselling, so that might be worth researching. EMDR is typically said to be helpful in processing trauma.
If you aren't on ADs, some supplements can also help, such as 5HTP, which is a serotonin precursor.
I'm not going to say much about it, because it's good to do your own research and make up your own mind, but do be aware that taking it with ADs or serotonin boosting drugs can cause issues.
Hope it goes well for you, whatever you decide.