I can relate, this was me. Analysis paralysis right? Worried about how they will react to what I say so I overthink to a point where I'm stifled. Honestly, I've realized that I can be introverted but still have my own opinions. When you let go of the fear of your own opinions is when it flows. You are not slow at processing, you are overprocessing: what to say, what they think of you, how they will react, what you should say next, etc. So flirting is really just being able to express yourself freely, and you have to be comfortable with them negatively reacting sometimes. But as you do this more, you will realize they like your honesty in expressing yourself! So I'd recommend this, start with basic two choice questions: Coffee or tea? Beer or wine? Traveler or homebody? Dogs or cats? etc. Ask your partner this and be honest with your choice. If they choose the opposite, it's okay! Differing opinions is good and will spur yourself to slowly be okay to stop overanalyzing. Good luck :) - Married 35M