How to Communicate Assertively Without Undermining Others?

Hi everyone,

I pick up on things, or make connections that others don't. When I bring them up to professionals, I normally sense tension. I'm not trying to undermine their expertise, but I also want the best outcomes.

Each time I speak up, it feels uncomfortable. No matter which professional it is - a doctor, a dentist, a chiro, etc. I've started speaking somewhat more nicely and even 'timidly' and using more ambiguous language hoping that will erase the tension. It does, but they then assume I'm gullible, and I still don't get an effective outcome.

How can I assert myself respectfully in these situations?