Thank you for your question as it will help many other young men and women considering #ButtockAugmentation.One should avoid the semi-permanent and permanent products such as PMMA and Silicone in the buttocks as the complications are too significant and serious, both short-term and long-term.Injectable silicone is illegal in many countries, including Canada, for very good reasons: too many problems.Hyaluronic acid is being done in some countries (and again, should be done by a board-certified plastic surgeon as complications can be extremely serious as seen in Brazil several months ago).Fat grafting is an excellent option - the so-called #BrazilianButtLift - yet, at 120 lbs, you likely do not have enough fat to "give". In my practice, I like to inject, after the harvesting, decanting and centrifuging about 800cc of 'healthy' fat per buttocks, which means I have to harvest about 2200-3000cc of total aspirate (aspirate includes healthy fat cells and stem cells, broken fat cells, oil, local anesthetics and blood).You best option is a round or pear-shaped #ButtockImplants and a sub-fascial intramuscular placement. Great implants are made in both USA and Brazil. If you have some fat to give, it could also be done along with the buttock implants procedure.But please, do not go for unscrupulous injectors who will inject illegal material in your soft tissues. Find a board-certified plastic surgeon. They are many good ones in Texas.Hope this helps.All the best,Dr Marc DuPere, Toronto plastic surgeon