Try using book shelves, furniture, drapes etc to tame the echoes you mention you're having trouble with. You'll have slap echo between two parallel surfaces so be sure to put something in front of one of the two parallel surfaces - carpet on floor or bookshelf on one side wall etc.
If all else fails, trade in the girlfriend; if she's this controlling during your courting phase, think about what she'll be like after years of marriage ;)
If all else fails, trade in the girlfriend; if she's this controlling during your courting phase, think about what she'll be like after years of marriage ;)