I'm pretty new to QGIS and geoprocessing. I have a layer of points representing traffic lights - where each point is a different feature:

I wish to create a layer with traffic light junctions based on this layer. My approach is to create buffer around each point - which I've done using QGIS:

But then, when I try yo dissolve them into single shapes, QGIS creates one feature for all the shapes instead of a feature per junction:

How can I tell QGIS to create a feature per junction?