Weight Gain after 2 years on protocol that helped me lose 60 pounds and maintain for a year

I set my protocol of 4 oz protein, 10 oz veggies and 1 fruit, IF of 16 hours, eating window of 8, joy eat of popcorn at the movies and I lost 60 pounds in 2017 and maintained until October 2018. I gained 5 pounds overnight and never could tighten things up to lose it. I have slowly gained 26 pounds since on protocol. My husband is trying to reverse his diabetes and choose to eat vegan in December 2018 so I joined him to be supportive. Doctor has checked glucose, insulin resistance, thyroid and blood work and all came back “normal.” I thought I had the magic bullet – IF and protein/veggies/fruit and now my thoughts are panicking. The month of May I thought “What’s the point?” and I’ve eaten whatever was around with no protocol. I’ve set a new animal protein/veggies and 1 fruit a day protocol of 50 carbs or less starting today. I had a plateau of 4 months while losing the 60 pounds but this has been a slow gain over 9 months and I’m scared I’ll be fat again. My clothes don’t fit and I’m committed to NOT buy bigger clothes but to figure this out. HELP!!