Fellow Clyde working on reform
Find a local group you can ride with or join a club if one is close enough to be convenient. Even the skinniest/ fittest/ fastest cyclist will applaud you riding your bike, and encourage you. Who cares what motorists think of you on your bike, you're working on your fitness, who knows what they're doing. Of you're close to your bikes suggested limit, you may have to spend more time inspecting your bike, getting wheels trued, etc; this is where a good mechanic, possible at an LBS comes in handy. Get a bike fit, you won't believe how much more comfortable your steed is.
Most of all, enjoy it, find an eating plan that works, stay hydrated, and keep pedaling.
Here's to many years of riding.