I relate to all the problems that OP writes. But what really worked for me was learning to work with my mind. Thoughts appear and they gradually & eventually disappear. The mental agitation will settle down if you learn to observe your thoughts. This is what I learned at Vipassana Meditation which is a 10-day silent retreat and doesn't charge anything (Pay what you can / donation model ).

Rather than taking SSRIs, I would prefer taking time out to meditate for an hour. It will give you focus for 8-9 hours the same as meds (I think) but without side-effects. Just my 2 cents.