I'm looking for some help specifying the type and dimensions of a new window header. The biggest complicating issue is that I only have 7.25" of depth to use for the new header.

The goal is to double the size of the window opening in a load-bearing, exterior, top-floor wall (only the 8:12 pitch roof above). The window header will need to go from a 5' span to a 10' span as seen here:

https://i.imgur.com/rATPh3K.jpg

This is what I know of the overall house structure:

https://i.imgur.com/bDkPUMC.jpg

My house is in Massachusetts and near the coast, so there are snow and wind load considerations. I'm in the queue for a couple local structural engineers, but there are not many in my area and consequently, they are generally booked out months. Wondering if this is a simple "use a 5.5-in wide, 7.25-in tall LVL or glulam" type question.