Sucking the boobs - I find it one of the sexiest acts. I couldn't find a good LoRA, so I made one myself. It was trained on around 750 images for around 14 epochs.
The best resolution is 768x768. Use bad-hands-5 to get better hands, and also try lowering the strength. The best values for strength are 0.7-0.9 . At lower strengths, it may not connect the mouth to the nipples but has less effect on style/content, so if you're aiming for that, you'd need to ramp up the gens.
Please use this respectfully and do not generate deep fakes of real people.