bunglie, you have so many decisions to make, don't you? and to me, an outsider I think what's really stopping you seeing your son - go for it - but then I look at what you have been through, how you have had to suffer the huge nighmare consequences of seemingly every day decisions and I just don't know what to say to you.
From where I stand, telling your son you will be in the area on Sunday, but also giving him lots of get out clauses sounds what I would do. However, you know the meeting with the aps will be a big one, and how will you feel having two such emotional meetings so close together? If you have a bad meeting with the aps, could this spoil the meeting with your son? And if you see your son before you meet the aps, will this make you too emotional to be the hard, reasoned, in control person you want to be? If course it could work the other way, knowing you are seeing your son, that will give you strength when you see the aps. I just don't know.
Another thing, is there any chance of your son finding out that you are seeing the aps? can you tell him what you are doing, send him lots of love but say this might not be the best time to see him as emotions could be running high? Is he likely to feel upset if he knows you have travelled to his area without looking him up?
My tip for the meeting with the aps is to listen very hard to their answers. I bet they won't answer your questions direct but will just repeat more of the same sort of rubbish they have been spouting for years. Pick up on this, stop them and ask them 'why do you say this? what is your specific reason? can you explain that to me more clearly? - just keep asking why, why, why - without pleading. Put them on the spot. And then write down their answers.
Has anyone suggested that you ask them if they believe their links with the adoption agency ever led to a conflict of interest? Pretty sure they will answer 'no' to that. So then say, 'why is that?, what are your reasons for saying there is no conflict of interest? etc etc. I would be very interested to know their answer (not that I expect you to write it here).
Keep going, bunglie - I feel you are nearly there one way or the other.