Congratulations on your engagement and pregnancy.
Wondering doesn't solve anything and certainly can make one crazy in time. It could be this or it could be that. Coming out and asking him is the best way to go - it saves on worry, headaches, frustration, anxiety, what have you, and gives you time to devote on happier and more creative things in life. Think good thoughts!
My very best to you and your new family.
Peace, Love & Happiness,
The Mystic Wave