If it were me, I'd rather people see me on the scooter, and frankly people shouldn't care about your size - they should be happy you are finding enjoyment on your bike and the outdoors. I too had a worry about the size of my bum in relation to my bicycle seat, I then decided, hey I was getting exercise so who the heck cares.
Congrats on losing the 4.5 lbs! At this time of year that's a great accomplishment and keep up the good work. Welcome to the site, you'll find all sorts of support here for your journey.