How can I fix a pointy butt?

Thank you for your question. Best procedure to alter your buttocks is a Brazilian Butt Lift. It consists in doing liposuction on your abdomen, waist and back and grafting fat to your buttocks. Fat transfer will change the shape and size of your buttocks. However, I do agree with the rest of my colleagues, you look beautiful as you are. 

Allow me to answer your question as best i can based upon your photos. However, please keep in mind that an in-person consultation with physical exam is first necessary before any legitimate evaluation or final surgical recommendations can be made.   That being said, because you’re so lean you are definitely not a candidate for fat transfer. I also would strongly dissuade  you from the temptation of a quick fix such as any type of fillers or devices such as Emsculpt which either have dangerous or deadly consequences or only temporary improvements and very costly long-term expenses for little result. Essentially buttock implants would be your only reliable permanent option. In the meantime I encourage you to continue working out and seeing if you can build the muscle and volume naturally. Glad to be of help. 

Hello dear!
Thanks for the question and provided information as well.
Based on your pictures, you are a good candidate for liposuction with BBL, and I think you'll get very good results.
Liposuction allows your plastic surgeon to transform your entire shape. You can improve your abdomen, back, hips and flanks, and of course your buttock, to give you a beautiful heart shape.
In general, you need to be physically healthy and at a stable weight, have realistic expectations, be a non-smoker and your BMI needs to be 30 or less.
l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)