How do you balance losing weight with having enough fat for BBL?

Trans woman here who is currently 5’6, 160. I would like to explore my options for a more feminine hourglass body and have come to rib modeling and/or BBL. The problem is I feel like my body is too masculine to my weight (not to mention having a lower BMI would be healthier) and I would like to lose weight. Ideally would like to be 120, but likely will sat 135. Either way, I’m concerned that I won’t have enough fat to lipo and transfer to my butt/hips. How do I balance a healthier weight w/having enough fat for BBL? I know I don’t want butt implants so that’s out. What would you recommend for someone in my situation? I know BBLs can be performed in patients w BMI as low as 19 but would you barely notice anything at that point? What other options do I have if any? Will rib Modeling and 360 lipo only (without or with minimal fat transfer) be sufficient? Thank you