Hi Joshgosh and welcome to the forum.
Well done on your weightloss to date.
It is possible your regime was so strict your body went into starvation mode, just a suggestion, so when you went back to eating whatever your body stopped being afraid of starving and was able to metabolise the food you were eating. I would say though if you kept up eating whatever you like you would most likely start to gain weight as a result.
You need to keep the body guessing and not let it get used to whatever you are doing to it. So you may find that eating strictly for 3 days and then a 'day off' so to speak or perhaps simply eat a few more calories on that day without going overboard. Alternate it like that so your body doesn't get used to the same thing. Also the body quickly adapts to any exercise routine so again give it plenty of variety wherever possible.
I am no expert but these are a few suggestions. One more thing you may want to try things separately rather than changing everything so that you can see what is really working for you.
All the best and let us know how you go.