Using a dummy with a shape approved by paediatricians is normal and doesn't cause the jaws to become misshapen in the first two years of life. Once all the baby teeth have come through, at around 2.5 years, dummy use should stop. Sometimes children make up for the missing dummy by sucking their thumb, but the shape of the thumb has a much more negative effect on jaw growth, so you need to be careful this doesn't happen. If necessary, it is better to let your child use the dummy for longer than to have them replace it with a finger or another object.
This answer is for general information. Your own case needs an examination by an orthodontist.