Ahh he's a little cutie, that's for sure! How old is he, do you know? His eyes and ears are so big I can't imagine he's fully grown.
It's really good that you're giving him a variety of veggies, just make sure he only gets one baby carrot a day (it looks like you just cut it up, and that's fine). This chart (
https://www.guineapigcages.com/foru...vy-Nutrition-Charts-amp-Poisonous-Plants-List ) is fantastic for showing good daily vegetables and which ones should be given less frequently. It's good to read it over and see where the veggies you give him fall on the list. Also make sure he gets 1/8 cup of high quality timothy hay-based pellets (Oxbow's good and easy to find in pet stores, but KMS Hayloft is prefered by some). If he is under 6 months, alfalfa based pellets are prefered so he gets a source of calcium to help him grow. And if you do not already, make sure he also needs UNLIMITED grass hay*, and that's it's green and fragrant.
It certainly looks like he needs a bigger cage, as well...If he is still young, this cage will do for a bit, but the sooner you can get a bigger cage, the better. Think of his cage like his house. Sure, he can come out when you want him to for floor time, but he lives and sleeps and poops and pees and plays in there. As such, it needs to be big enough for him to exercise when HE wants (they run laps around cages or rooms for exercise, and popcorn when they are happy), while also giving him enough space that he doesn't have to sit and sleep in his own urine. And believe me, mine was in a cage like your's too, and some days his bottom was wet with urine even though I did a weekly cage clean. Now that he's in a 2x3 (I hope to expand and get him a friend asap) and his change in attitude and health is crazy...he popcorns all the time now and has a couple big cozies/hides to lay on/sleep in and he doesn't have to sleep in his waste any more.
So saying this, don't feel too bad that he's in a small cage. I mean, don't brush it off because he DOES need a bigger one, but most people here started out the same way! Ask around, tons of people made lots of first-time mistakes...small cages, inadequate food, mis-sexed pigs...the whole deal. But just like you they all, including myself, love their guinea pigs and research and learn how to give them the fantastic lives they deserve.
*Good grass hay: timothy, orchard grass, blue grass, etc.. Do not give alfalfa (which is a legume, not a grass) to adult guinea pigs as it has too much calcium and can cause bladder stones/sludge. It's good for babies though, although they should only have one source of calcium and maybe some higher-in-calcium veggies. Meaning, give alfalfa hay + timothy pellets, or grass hay + alfalfa pellets.