Symmetry of lip fillers and corner of the mouth Botox to improve thin and volume-less lips

Both my upper and lower lips are very thin and completely lack volume, so I often hear that my overall impression looks somewhat cold and sulky. Furthermore, the corners of my mouth droop downwards even when I am at rest, which often leads to people misunderstanding that I am angry, and it is very upsetting. I am considering getting both lip fillers and lip corner Botox at Maypure to achieve the plump and vibrant lip line that is currently in fashion. I am wondering if the procedure can correct my asymmetrical lip shape, and I would like to know how long it takes for the injections to settle naturally. I have heard that lips are very painful because they have a high concentration of nerves; please let me know the level of pain and whether it is possible to apply lip products on the day of the procedure.