No jawline - what procedure would help? (photos)

Yes, you are being harsh with yourself. Sometimes, it is not as bad as we think it is.
You have options, but the number one thing we need to do is understand and specify what you feel is lacking in your face and look overall. We must weigh the options and possible solutions because you have several.
We need to differentiate the health and aesthetic-related reasons for your needs. Each reason requires different methods, and some are more invasive than others.
A chin custom implant alone may not necessarily solve your discontentment, and you may need a combination of custom implants. Neck liposuction or neck muscle tightening could potentially be another solution, but to provide you with an exact solution, we would need to specify and understand your exact needs.
My team and I can help you identify the best solution for your needs, but you need to be very specific.
Best wishes

An underdeveloped lower jaw is lacking not only in projection but also width. If these features are lacking, then there is a lack of definition of the jawline. Ideally one considers orthodontics if the 'bite' is non-ideal; but a masking approach with a genioplasty and jawline augmentation from the 'angle/ramus' to the chin is often preferred. The results are impressive and natural when done appropriately