I plan on going down to a nearby lumberyard who has the sizing software.
Please report back on the results. If we don't hear anything, I would assume the lumberyard could not give any detailed advice our your situation. Also whether or not they will provide that Engineer Stamp.
That would be a remarkable lumber supply store that was brave (foolish?) enough to specify a beam for your house based on a diagram you supply them. That is what structural engineers and architects do for a living, but I suppose if a lumber supply place happens to have a licensed engineer or architect on staff who is willing to design your beam, go for it. I assume they would charge you appropriately.
Actually the service was free
And yes - it was sent out & stamped by an engineer