Health issue ?

I have a doctors appointment this Thursday. Reason I’m seeing the doctor is because of a personal health issue. I just want to have a normal life. My wife and I have been married for almost 3 years. My parents want a another grand child in the family. When my wife and I engage in foreplay my penis doesn’t get hard, but with the Cialis pills my penis gets hard 100%. Without the pills my penis gets 60 to 70 percent hard. A couple of days ago when my wife and I were having foreplay, my penis was 70 percent hard when we were ready for sexual intercourse my penis went soft. I can’t try oral sex because my wife don’t like oral sex. She says she could get a disease from oral sex. 

What could be causing the problem of my penis not getting a hard on? Is it because of these reasons?

-Hormones 

-Thyroid problem 

-Stress

-Nervousness during sex

-Does sex have to do with the mind (brain) 

How can I fix this problem? I’ve tried cardio exercise (Treadmill exercise) to increase blood flow to the penis. I drink a cup of coffee before bed I eat a banana every day. I’ve tried foods that help with the blood flow to the penis.

Is there a supplement I could take that’ll help with the blood flow to the penis? 

When I go see my family doctor, I ask him to do a check up on me (blood test)

Is it time to see a sex therapist? 

Has anyone seen a sex therapist? 

What questions will a sex therapist ask me?