I think I have a small pinguecula on my eye. I am really afraid it will get worse. Is there anything I can do to prevent that?

Not really. Pingueclua are a normal response to wind, dust and uv light. They are the eyes defense in the middle years to these external forces. They have no symptoms and are usually unnoticed. You would have to hid in a cave for many years to prevent its development. The eye grows them for protection.
A few things. Pinguecla are small raised areas on the sclera (white part of the eye. They usually do not require treatment. Things you can do that may help prevent a pingueculum or keep the problem from getting worse include: keeping the eye well lubricated, wearing good quality sunglasses avoiding eye irritants.