It's not at all terrible! You submitted exactly what they asked. I originally had 2 and the last course I took ended up being an opportunity for a third, but I wasn't initially counting on it.
I think the content of the letters matters most! My husband hires a lot of people and in his opinion, letters go a looooong way in vouching for someone and revealing their strengths (or weaknesses). If you feel confident your recommendations represent who you are and what you have to offer, then 2 letters is plenty!