I feel your pain, Joshua. The fact is, a home estimate website is a computer running an algorithm that can't take into account the whole picture. It's not intentionally undervaluing your property, it just cannot take into account the full picture. Even as a Realtor, nearby current listings are only a part of the comparables. Recent sales and expired listings also must be considered when coming up with a value estimate, not to mention condition, features, etc.
Long story short - ignore any online value. At best it's a ballpark figure, at worst totally misleading and inaccurate. No educated buyer will even bother with an online value - it's part of my client education too show just how misleading these can be.