DO NOT try to "artificially sweeten" it by adding sugar, that just won't taste right. Cook some carrot chunks partway, and add them. The sweetness they have naturally will help some. You could even caramelize them some (easiest by roasting them until they are a little bit brown), which will concentrate their sweet flavor even more. Or add a lot of onions that you've sautéed to the point where you've lost the sharpness and just have the sweetness.
And please let us know what you did, and how it worked out! This should be the start of a good relationship between you and ChefTalk. Welcome !