So
So while I've come across some of these problems, I didnt have hear the issues it sounds like you had

I did learn early on that if the girl has trouble taking it, LUBE LUBE LUBE lol you have to do a lot of foreplay playing with her pussy with fingers, a decent size dildo. The body WILL stretch, its can squeeze out a baby. Then when you do fuck her the body needs to adjust. Because you're big its usually tight in the pussy which causes more friction and makes them sore, lube and more lube lol. Teeth on BJs was sometimes a drag. I'm not a fan of the whole gagging BJ thing but deep throat is fucking awesome when they can do it. Go for it, work it, get used to it so you can control your gag but if you're just gagging yourself thats not accomplishing anything. Just give me a blowjob and go as deep as you can.
I've been lucky to find several girls that have been able to deep throat my dick which is pretty fucking awesome

. Same thing for anal, that really takes some prep on their part with dildos/butt plugs. You wont usually have the cant go deep problem in the ass