I totally get this, it's such a tough spot being pregnant and having a clingy toddler at the same time. It's fine to carry him sometimes, but might be good to chat with your PD or gynae about what's safe for your back and belly at your stage of pregnancy, since every pregnancy is different. A few of us mums try to redirect by sitting down and cuddling instead, or making it a game where he "helps mummy" with light tasks so he feels needed without you having to lift. The good news is they adjust over time, especially once you explain in simple terms that mummy's tummy has a baby growing and needs rest.
Experiencing this too, keep wanting to climb all over me hahaha had to remind her got baby hahaha but don’t overstrain yourself too. Just remind him that mummy has a baby in my tummy and switch carrying to maybe a hug instead and etc? 😊