Has anyone ever considered that birds evolved from Pterosaurs?

Yes. One of the early great pterosaur researchers H.G. Seeley proposed this idea and never gave up on it. However, the only things birds really have in common with pterosaurs (flight, pneumatic skeletons, beaks and body fibers) are either clearly convergent (flight) or are also shared with dinosaurs (beaks, pneumaticity, fibers). So on the basiscs, there's no reason to pick pterosaurs as an origin ahead of dinosaurs, but dinosaurs share huge numbers of characters with birds (feathers, furcula, retroverted pubis, shape of the humerus, specialised shoulder) and there's some huge differences between pterosaurs and birds (wing membranes, elongate 4th finger, odd neck vertebrae, different palate etc.). In short, there's no reall support for the idea and still tons in favour of a dinosaur origin.