Mr dr is adamant that I cant take buspirone long term despite it helping me

I have bpd and cptsd, I was originally on diazapam but I got used to it and it became inadequate, I mentioned that I wanted something that could with my every day hyperarousal rather than medicating when I get too overwhelmed/non addictive and he suggested taking 5mg x3 day of buspirone, ive had it for 10 days now and I actually think it works better than my duloxetine 90mg(for mental health and fibromyalgia) so today at my follow up i said I wanted to continue but he again said its not safe long term but I cant find anything to support that online and he thinks the talking therapy ive been referred too(despite already having 2 years of specialist therapy ) is going to be enough to somehow manage my physical symptoms for me. He agreed to give me another 20 days worth but thats it. What do I do? (Im in england)