Implants can look natural, but I think it must be down to employing a good surgeon, because many don't.
Before opting for something so drastic, make sure you talk it over with medical folk with your best interests at heart. Sometimes what you think will make you happy proves not to 'do the trick' after all. If you can work on your self image then it may do more for your sense of well-being than surgical shape changes.
A loving partner may like small, medium, or big boobs, but what they most like is not having their partner put themselves through risk for something that ought not be so important. If you have thought it over and are convinced you simply can't accept yourself as you are, then go for it. But explore all other avenues first.