It's probably true to say that all fictional characters are based, to some extent and in different admixtures, on actual people. The secret of not getting sued is to make sure none of them is identifiable as such. It sounds as if you're doing that. Inadvertent libel is theoretically possible, but I can't remember a case. Though I hasten to add, I'm not a lawyer.
The disclaimer is certainly helpful, though it wouldn't cover you to deliberately libel someone.
The main danger - not the only one, but probably the likeliest - is to use a name you've invented only to discover that someone who also matches the description in other ways has the same name. If you're going to have a murderous dentist, solicitor, architect or other professional, Google the name and make sure there's no one in that profession with that or even a similar name.
Human nature being what it is, this may be less important if your dentist, solicitor, architect or whatever is described as being the world's greatest lover!