Terrifed of labor...PLEASE ADVISE

Hello ladies,
​So im 35 weeks and 3 days now..just had a docs appointment yesterday and my fundal height is measuring about a week ahead. Also had an ultrasound at 33 weeks and baby was measuring at 80th percentile. Doc told me today that it will most likely be a big baby..bt she was very unconcerned about it. I on the other hand, am completely freaking out! This is my first pregnancy, things already havent gone as planned. I have gestational diabetes which is being controlled by metformin and insulin. 
​I should also mention im quite short and apparently the baby is quite tall because femur length was well above 90th percentile at 33 week ultrasound. I have another ultrasound next week. 
​I am basically terrified of giving birth and am starting to have panic attacks as time draws near. I want to have a natural unmedicated birth but i dont kno if i will be able to do it. Im scared that what if during delivery i literally CANNOT push my baby out because i go into panic mode?
​For first time moms who have already delivered, naturally, can you please give me some tips?
​How can i overcome this fear?
​Also, for those who gave birth to big babies...was it unbearably painful?
​I need to mentally prepare myself. 
​Im REALLY REALLY scared! :'(