Background info:
Northeast of Seattle
2004 built 2 story, crawl space, master on main, a little under 2100 sqft, typical track home build

I just purchased this home in early October and have not been really happy with the current Bryant 310AAV, 44k Btu, 80% LP gas furnace. My main complaints is that it takes roughly 3 to 4 hours to warm the house from 65 to 69 degrees and that the air coming out of the registers is lukewarm at best. When the system is on (averaging about 9 hours a day, up to 13 hours when the temp was in the mid 20s), at the closest register to the furnace I am only getting roughly 90 degrees of warm air out of it. Most of the time it feels like the house has a cold draft when the system is running.

I set my thermostat to 69-70 when I am home (mornings, evenings and weekend) and set it back to 65 when I am gone and at night. Normally I like to set the thermostat to closer to 62 when I am gone and at night but the, what I feel is, slow recovery time makes it unreasonable. I’ve had the furnace serviced right after I purchased the house.

Comfort is very important for me and I am contemplating adding an AC unit for those few weeks that are warm and would also consider replacing the furnace at the same time if it is undersized.

From reading the forum so far I realize that I need someone to perform a Manual J calculation on my house to properly determine the correct furnace size, but judging by this limited information I presented, do you feel that this furnace is undersized? Any advice or opinions would be greatly appreciated!