i could give such an indepth explantion to why our faces become asymetrical from our early child photos to our mid twenties blah blah blah...but giving you the solution is far more simple and less stressful.
having your face lobsided to the left or right is only releative to which side of your brain is most dominant.
dominant side of brain build better neuro paths to control facial muscles in the opposite side of face.instinctively the brain triggers those muscles regurlary in responce to all your daily emotions and facial reflexes (smiling,squinting,chewing,anger,frowning etc)
years pass by and the result is muscle mass has firmed up and hel pull the skin around the contours of your jaw,cheek,eye socket blah blah blah, but the increased muscle mass has also created defined crease lines around nose, mouth eye socket and so on.
should you anaylise your facial lines when you smile you'll notice straight away.
now the weaker side of your face only has minimal muscle, with poor communication paths to your brain resulting in poor control and reflex.
you have to take note of natural facial epressions on your dominant side , study the muscles which are used. they wil be the muscles you'll need to train and build in your weaker side.
building the exact same muscle on the corresponding side will inevitably lead to a more balanced symetry.
facial muscle take about 3 months of everyday training (1hr) to become increased in mass,this muscle is built on top on the bone structure pushing the fat and skin layer up to give you more curveture around cheek bones and stop that long flattend look to the face etc.
look on the internet at muscle diagrams of the face , find out the names of the muscles you noted you need to build and train, then google the muscles and you will find specific exercises that will help you.
you will not see results in one bloody week okay... but with dedicated traing you will notice the effects around bone struct within a couple of months.
i understand how you feel but be motivated and patient, when you locate a muscle and then try to have the relaxed brain flex this muscle you may find it only twitches a tiny amount but that is good and with constant practice the twitch becomes stronger and more easily located by the brain the next time you train it and eventually the results will definately show.
remember to let the relaxed brain control the muscle as you are trying to build and strenghen neuro pathways which means this newly trained muscles becomes used instinctively by the brain when you genuinely smile etc.