Struggling with faith, procrastination in prayers, and falling into sin - need advice

As-salamu alaykum. I'm not sure where to begin, but I'm in the prime of my life, married, and expecting a child in August, inshaAllah. Lately, my imaan feels really low. I keep falling into major and minor sins, no matter how often I try to stop. When it comes to salah, I'm so lazy. Every morning I tell myself I'll pray all five, but then I only manage Dhuhr and Asr-the others just slip away. Even when I do pray, I yawn constantly, even if I'm not tired. It's frustrating because I know what I should do, but when the time comes, I don't follow through. I've tried some things to improve, but I always go back to my old habits, and the guilt eats me up. Right now, my prayer situation is at its worst. I'm not sure what kind of replies I'm hoping for-I just needed to share this somewhere. Maybe it'll help. JazakAllah khair.