Sorry for the slow reply. I replied to your post om "Where's the picture" then managed, on a poor internet connection, to sign out of Walkhighlands and couldn't remember my password to get back in until now.
My original thought was Loch a Mhuillin on the Sandwood Bay path, but I got distracted and forgot.
I know the feeling. As you are so close I am going to give it to you. You were on the right path but it is Loch na Gainimh, a little before you get to Loch a Mhuillin.