that's coming from me

[frindle2]

Hello. Would you please tell me what underlined part means in the context below?
Does it mean 'I can't believe I, the most awkward person in the world, have OCD' or something?

(It's story about a boy with Obsessive-compulsive disorder. April is the boy's only friend.)
"It's a way in which your brain can go funny. They called it OCD. I remembered it because Lauren always says she's OCD about her pencil case.
It sounded different to the way Lauren says it, though, because Lauren made it sound kind of cute, but this... well, it wasn't cute." says April.
I have never been less sure of what to say, and that's coming from me, the most awkward person in the world.
I am wondering if this thing April is talking about is the reason I had to go for that assessment back in Essex? The one that we still haven't heard anything from.



Source: When I See Blue by Lily Bailey

 

[Barque]

People who're awkward in social situations often aren't sure what to say.

He's saying he's very awkward and often doesn't know what to say. He's also saying he's never been less sure of what to say--he means he was very very unsure of what to say at that time, added to the fact that he often doesn't know what to say. Combining the two statements, he means he was completely at a loss. He had absolutely no idea what to say and was feeling extremely awkward.

That construction is a way of emphasising that he just didn't know what to say. Don't take phrases like "the most awkward person in the world" too literally. Such phrases are deliberate exaggeration used for emphasis. You can't measure awkwardness.

"That's coming from me, the most awkward person in the world" means "I, the most awkward person in the world, am saying this (that I've never been less sure of what to say)".

Or, to put it differently, it means "Those words are coming from me, generally an awkward person, and in this case I felt the awkwardest I've ever felt".