First rule out any health issues that might cause weight gain/prevent loss, such as hypothyroidism, insulin resistance,
PCOS, etc, then work on cutting calories
and getting plenty of exercise. You have almost 6 months, if you start a meal/exercise plan and stick with it, you should be able to lose the weight by Aug, provided you don't have any untreated medical issues, holding you back. If you haven't been tested for any of those things, you should be.