Even when I could only afford a cruise one a year or, more often, fewer, my TA fowarded me the advance releases of new cruises (before they are open for booking), and if I found a cruise to my liking, I would ask her to pre-book it with my specific staterom request. She did it.
If I had reservations in place when sales come out and if my sailing is included, I would ask her to price the difference for me. She would read the fine print and sometimes the sale would be advantageous and sometimes not. If it was advantageous, she would rebook with the sale price.
She does not travel with us.
In all cases, we received refundable SBC, free gratuities, or both.
You seem set on not using a TA. So I would recommend you do it your way and move on.