Vial quality

I have a question about how the degradation process may affect the effect. Thank you in advance for sharing your thoughts.

My ED is entirely psychological. I keep the vial in the back of my fridge. When I had a fresh vial, I got excellent results with 9/10u at home (without a partner present). I had successful sex with a woman a few days later with 15u.

Then I travelled to another continent and took my vial with me in an insulin travel pack (with ice packs) - hand luggage. A few days later, I used 15u and did not have a noticable effect - this was frustrating because I was with a woman. Maybe I missed the sweet spot.

Then yesterday I used 20u and I was rock hard but I needed considerable stimulation.

My question is how fast the deterioration process when keeping the vial in the fridge? Is it normal that when you start a fresh vial, it works much better than a couple of weeks in?

Is it a good idea to up the dose in line with how long I have been using the same vial?

Is it better to freeze it? I keep reading conflicting stories about freezing and dethawing it.

Is it a viable path to prep syringes and freeze them and use them with needed? Or is this a bad idea because of the plastics etc

Thanks for your thoughts.