no matter how much I pay attention

[flytothesky]

Hello~ Can you help me say this naturally please?

Manager explains to A the flow of their project.

Manager: Did you catch the flow now?
A: Yes, thanks for your time.

A and B is talking about the project.
B：Did you really catch what the project about？
A: ⓐNo, no matter how much I pay attention, I couldn’t catch the flow of the project.
B: Then why did you said ‘Yes’?
A: ⓐI was afraid if the manager thinks I’m stupid.

[Tdol]

How about:

No, no matter how much attention I paid, I couldn’t catch what the project is/was about.

I was afraid that the manager would think I was stupid.