Thank you for sharing your concern.
Unfortunately, our society is largely based on the superficiality of things. We have been conditioned for generations about what good looks should look like. Hence your mother's concern of finding a suitable guy via arranged marriage option. I'm sure you are aware of the love your mother has for you, and this comment could be due to her own conditioning as she was growing up.
However, looks and success of a marriage are unrelated. Finding a groom is one part of the story, being in a mutually comfortable and respectful relationship, with warm feelings for each other will strengthen your bond, thus making your journey as a couple a lifelong pleasant experience. If you are unsure of the guy you are dating, have an open talk with him. Discuss your worries/fears/apprehensions with him. See if you'll are on the same page, where your future is concerned. Do not compromise, just because of your fear of ending up alone. Take some time alone, write down your expectations from your future husband. Where do you see yourself with this present guy 5 years down the line. Be realistic in your expectations, but do not compromise just to envision a happy future. It is better to wait for the right person to come along, rather than settle with whatever you have, in the hope of making it right in the future.
There is someone special for everyone. If the present guy is not the right one, when the time is right, the special guy will come along. Do not be too worried about it.
Best wishes to you!