Relationship advice please

My SO and I have been together for a little over 5 years, we started living together about 2 months after dating. I have a 9 year old daughter from a previous relationship and my SO treats her like his own. We decided to start TTC 2 years ago with a mc a year ago. I'm starting to wonder why he hasn't proposed. He's totally on board with having a baby with me, so shouldn't he be willing to make more of a commitment to me as well? I try not to let it get to me but sometimes it does!