failure to thrive... please help if you've been there

This is long, but i am seeking advice from parents who have been through Failure to thrive and food allergies.
So my 6month old son has been diagnosed as Failure to Thrive since July . He weighed 6lbs 3oz at birth and weighs 11lbs 13oz today.
We breastfed to some degree at first, then had to bottle feed pumped milk because he would scream at the boob his first month of life. Constant spitting and arching, crying for hours. Got put on Zantac for reflux. It sort of helped. Ended up on Prevacid for about 2.5 months.
I exclusively pumped ... 2 hours a day for several months and fed him my milk. He had blood in his stool and the spitting up was constant. so i took dairy, soy and egg out of my diet. He started falling off the growth charts. 
We added Nutramigen to my milk and he ate pretty well 20-24 oz a day. But still spitting and not gaining. 
Spent a week in hospital for GI tests to reveal all is normal... Just GERD. So we take him off breast milk entirely and are on Neocate and Duocal for severe cow's milk protien allergy. And now we're on Nexium for GERD.
still not gaining!!! If he doesn't getback on  the curve by Nov 1, the specialist will insert an NG tube to make sure he gets enough food. 
Fortunately, he is reaching all his milestones and is pleasant with the GERD meds.  But Mommy and Daddy are exhausted from the stress and from waking him through the night to force  feed him. Now he is teething and refusing to eat.
Has anyone else struggled with this situation? Any insight would be so appreciated. My anxiety is constant. My husband  works FT and I am a FT teacher in elementary school. The stress and guilt are taking their toll on both of us 😩 We have no life.