Back on track

Fell off the wagon... Seems to be a pattern. I do really well for a few weeks, lose 5-10pounds....then get off track for a week or 2 and gain a few pounds back. I don't want to fall off of track anymore!!! I have a total of 73 pounds to lose before next July/August. I've already lost 10lbs or so. I'm getting married next November and I REFUSE to be fat on my wedding day!
I'm a stay at home mom, I have 3 girls, ages 9 months, 2 and 4. I like to do Zumba and I'm restarting the Couch to 5K program tonight. My goal is to run a 5 or 10k in May.