House not warming up

So I need some help. I recently replaced our old diesel furnace because of fuel costs. I installed a 60,000btu electric furnace that we purchased from lowes. The new furnace went in fairly easy right on the old floor mount of the furnace. wiring was easy, it was a dual 220v that we had available for power. If I don’t add another heat source such as our pellet stove or leaving the oven door open it will not get higher than 67 degrees in the house. I cannot afford to hire a professional to come tell me what needs to be done. Trying to figure this out with help. According to the manufactures chart the 60k btu should have been just fine for our 1400 sq foot house. I don’t know where to start to figure out what’s going on..I.e. air flow issue, not enough but’s etc.. any help would be appreciated.