I think you need to start over from you ellipse. Extrude each loop from there and for the front part simply select only the lower half and then extrude. That should only produce quads and no tris.
nope, am actually an electronics engineer. 3d is my hobby currently, though i’d be glad if i’ll find a job related to it! 
am looking at architectural visualization
triangles really do bad, selecting the triangles you want to convert to a quad and pressing alt+j will do the trick. although, as what musk said, try reworking the model from the ellipse and extrude from loops, that’ll give you a cleaner mesh…hopefully free from triangles.