Welcome to the forum and well done for posting which can feel quite daunting the 1st time. I'm sorry to hear what you have been going through along with the amount of time that has passed before being able to speak to someone who does not appear to have helped you.
As far as attempting to obtain a second opinion you are more than entitled and sadly/seemingly this is something that you may have to fight for (which is really hard when you are suffering..) I can't tell from your post how supportive your GP is ? or whether you feel going back to them (given the long delays of anything happening), is likely to result in more immediate assistance.
I'm struggling to understand why the psychiatrist was not able to offer a more comprehensive plan ? Did they offer additional follow-up sessions ? as these things are not (as you well know) done and dusted in a single phone conversation, it can take many meetings ... with little to tiny steps made along the way and at the time these can feel in the wrong direction too -
I don't know if any of the above will help you, but rest assured someone cares!