You look just fine to me. I think it’s the shorts that make you look like you’ve got a bit extra around your hips, being tight and all.
Not bad, not bad at all.
I suppose, theoretically… but then I shouldn’t be eating more anyway, should I?
You’re definitely not underweight.
Maybe bordering on overweight. You’ve got a layer of fat around the middle. I wouldn’t put on any more weight, certainly not 20 pounds.
And, I reached my quota of looking at men in bike shorts on the internet a little early this year.
Put me strongly in the BMI means squandoosh column. It’s better to have a little bit of extra fat and be healthy, than to look good and be unhealthy. From what you described, it sounds like your health is fine.
Now, to temper my comment on your physique, I’m a gym rat, so from that perspective, you’re lacking somewhat in muscle tone. That said, based upon the type of exercise you get, that’s expected. That is, functional training will generally get you very strong but do little to be “aesthetically pleasing”. But in all seriousness, your physique looks fairly average to me.
If you want to have a little more muscle tone, the only really “easy” way to get it is from some weight training, but I would certainly say that 20 lbs. is a LOT of muscle. However, it really sounds like a body image issue to me, such that even if you do get a little more tone it may not make you feel much if any better.
What I tell people when they ask me about fitness, like a goal for weight gain/loss. I always tell them that how they feel (in terms of health, mood, etc.) and how they feel about how they look are FAR better factors by which to judge than weight, BMI, inches, etc. People tell me they want to fit in a certain size pant or lose X lbs in Y months; IMO, 9 times out of 10, their goals are either unrealistic or not ambitious enough. OTOH, as long as you are feeling healthier, getting more energy, and feeling better about how you look, then you’re always meeting your goal and you’re always inspired. I guess it’s sort of a zen approach to fitness… without the yoga.
You look average to me, and if you’d like to gain weight, I suggest putting it on in muscle, although 20 lbs. of muscle might be a bit excessive.
Just another opinion popping in. Obviously, you are healthy. I think the problem is you have such a broad chest/torso. This makes your limbs look small in proportion to the rest of you. You have nice legs, but again, they may look ‘undersized’ because your shoulders are broad. Obviously, the choice is up to you, but if you enjoy working out, adding some bulk to your shoulders, upper arms, and legs wouldn’t look amiss. You seem to have a frame that could carry more muscle than you currently have on it.
note: IANA personal trainer, and I could stand to lose a good 40lbs. I’m just trying to get you to the pinnacle of studliness 
Thanks for all the replies, it seems I may be being a little hard on myself. I don’t mind the little fat i carry around my midsection, I much prefer it to struggling for that six pack. I guess that hitting the weights wouldn’t be a bad idea, if only to tone up a bit. I’d like to balance out my limbs, but like some of you have pointed out, my breadth of shoulders and chest might make that difficult at best.
So gym rats, any advice? I’ve got a decent set of free weights, 10-40 lb dumbells, up to 200 lbs bench and a curl bar.
Difficulty: Bad knees, so repeated squats and the like are out. Finances aren’t there for a gym, so it’s ye-olde fashioned method for me.
I’m no gym rat, but I highly recommend shovelglove. I do it and it’s made me noticeably stronger.
Seconding shovelglove, the Superhero has been doing this off and on for a few months and it’s made a HUGE difference in his body shape (gained muscle, lost fat) and also his self-esteem.
I think you look fine, btw.