You shouldn’t feel silly at all. I know exactly what you mean as I work many hours too. When you suddenly have time for friendships you haven’t too many (and they may be at work also.) If you have time for a ladies shiur/parenting class (Shabbos or evening), the discussion following this type of thing can lead to a real friendship.
Also, the neighbors in your building – sometimes things will happen to develop a deeper relationship. Not just borrowing, but ask advice on recipes or making a simcha, schools camps for kids. You can possibly build on the neighbor relationships until they becomes a friendship.