A year away is PERFECT. You can do a heck of a lot in a year. If you do it right, you could honestly lose a third of your current body weight (there are examples of that right here on this site).
But you don't have to. I would recommend relaxing a little. Maybe get a mani/pedi, get some new makeup, buy a new outfit that you love. Get more accepting of yourself. Just lose a little weight at a time. Take it slow for a while so it isn't overwhelming. You don't have to lose all the weight now or even ever. And just a few pounds helps a lot in terms of how one feels (at least for me it tends to).
Maybe don't try to lose weight so that you can like yourself better (be it because of how you feel, look, etc.), but instead lose weight BECAUSE you love yourself. If that makes sense. It works way better that way.
Don't let this derail you. You slipped, now get back to it. That's the only way to keep going.
I hope this helps even a little. I've slipped up big time a LOT. It doesn't feel good. But hang in there! It's going to take time and effort for all of us.
And congrats on the engagement!