What is the average duration of cheek filler?

I went on a really intense diet, so I lost weight in my body, but I lost weight in my face so fast that I ended up looking like a skeleton ㅠㅠ My face looked much better before the diet.

I look so haggard that everyone around me asks if I'm sick, so I'm seriously considering adding volume. I've heard that filler injections are the most immediate and effective solution, but now that I'm actually about to have foreign substances injected, I'm worried about side effects, and what I'm most curious about is how long the filler lasts.

I'm really struggling to decide because there are so many recommendations and non-recommendations regarding fillers. First off, how long does the nice volume typically last when injected into the cheeks or nasolabial folds? I would be so upset and feel like I wasted my money if it completely collapsed in less than six months after just one injection. I know it varies greatly from person to person, but if those of you who have had it done could honestly share your experience regarding how long the filler lasts, it would be a huge help in planning my budget!