Double chin: how to tell if it’s genetic fat deposit or lymph fluid/stiff fascia?

I do myofacial massage/stretches/guasha like 3 times a week and seeing little progress in my double chin/receded chin. I’ve got my tongue tie cut 6 months ago and again, minimal changes. Any recommendations or ideas on what else I could do to address this?

I’m slim (53kg) and very fit, drink little, don’t eat much sugar if at all… my posture isn’t great- yet to address this properly as I have hypermobility so stabilising muscles work overtime all the time urgh

Anyway! Keen to hear your thoughts ☺️