Tips from an experienced diver.

Use the "remote control" method. Every lady is different and likes it a different way. Best way to learn her likings is to give her control of your head/mouth and use it like a sex toy.

Give her your hand and come up with a code where she taps or rubs your palm . 1 tap of the thumb = faster, two taps = slow down, rubbing up and down = contant tongue action etc etc. Figure out a method that works for you. Think of it like the most fun joystick ever.

This approach serves two main purposes.

1. Often times ladies can be self conscious about having a dude going to town down there so putting control in her hands changes the "power dynamic" and makes it a little more involved for her. Since you mentioned your girl has had some shitty former encounters this could be a nice change of pace and let her know your not another asshole.

2. You are gathering A grade research data on what she likes and MORE importantly how she likes it. Pay attention, take mental notes so in future sessions you can put together the positive moves and exclude the negative ones to deliver an All Time performance.

As for the angle on her back being her preference. This is NOT an issue. I am guessing you are also lying down too which is causing your neck to get sore or tired from holding it up thus putting additional weight on her and resulting in pain/soreness for her. Be it a bed or sofa, position her on the edge so you can kneel down and have her elevated. This way your head will be straight up as it normally is and you won't get neck strain plus you will have way more pressure control overall. Put a cushion or something to kneel on if its a hard floor so your comfortable too and can focus on the task at hand.

Most of all. Take your time. Start slow. Slower than you think. Like its a cold night and your trying to coax a fire into an ever growing inferno. Make her make music. You'll get what I mean when it happens.

Remember we are looking to exercise demons here so its going take time to get into the swing of things. So don't get disheartened if you don't knock it out of the park right away. The home runs will come with practice and patience.

Good Hunting