Blowjob gag reflex

So I gave head the first time last night and I did it for about 3 mins but then had to run out to the bathroom to spit and drink water. I COULD NOT STOP GAGGING NO MATTER HOW HARD I TRIED! I gag on my own toothbrush ffs, I’m hopeless. I walked back into my boyfriends room and he had his head in his own hands upset, as it was also his first time getting head. I explained to him that I have a really bad gag reflex and that it wasn’t him and he understood. I felt absolutely horrible and want to give him a better experience next time but I don’t know how to get past gagging. Please help me, any advice will help