This is the crux of the matter - "am I this, or that"? Perhaps (NSFW
will help you visualise why it can be so difficult for women and saddle happiness.
The range of anatomical variety is great, so rather than worrying about your external tissue, focus on the internal structural support (ie, the pelvis)
All of the suggestions here are good, but don't get ahead of yourself too soon.
I'd recommend an order to the solution - nail down the basics, then progress to the details. It may not be 'one' thing that is the root cause, but a collection of misalignments that add up to Lady Bit Problems (LBP)
Bike Fit: please ensure that her saddle height/fore and aft are within recommended range of motion. Saddle to high or too low can create discomfort no matter the saddle. Also handlebar height can be a factor in excess pressure in the LBP area.
Cycling shoes: Don't have to go clipless, but a stiffer shoe will increase stability and comfort at all contact points. I like to say that you don't 'sit' on a bike, you stand on it. Soft squishy running shoes are poor platforms for pedaling, consequently your pelvis is compensating for instability at the feet.
Bike shorts: bike shorts bike shorts bike shorts bike shorts. Tessars' comments very good!
Saddle: Yes a cutout can be 'the thing' for LBP, or it could be the sensation of your LB's going into the hole and getting pinched. Hole size/depth and placement should reflect your forward rotation. The more forward you lean, the more you are off the 'sit bones', but on to the face of the pelvis (the Pubic Rami). Irregardless if you are an innie or an outie, the internal structure needs to be supported so that you are not supporting yourself on your soft tissue.
FIST/SICI/FIST DOWN DEEP