I suggest you look at Airbnb and VRBO instead of hotels, especially since you have over a year. We have also found that many them do not post availability until about a year out, but you can sometimes ask for them to open it and they will comply. We have switched from hotels to Airbnb and VRBO and will be staying in France this spring for almost 12 weeks. Nothing like being able to get up and walk to a nearby bakery to get fresh croissants to eat in your cozy kitchen or out on your balcony. It's also fun to get deli dishes and local wine for an inexpensive and easy dinner at home. HINT: Carefully use the filter options to reduce the sheer number of offerings and get the features you would like. For us, cancellation policy, dish washer, on-site parking and clothes washer are important. Affordable places with air conditioning are a rarity. You'll likely find that hotels end up being more expensive with less room and of course, no kitchen.
By the way, we booked a townhouse in Honfleur in July for 7 nights for $827 total, all included. It has secure parking, 2 bedrooms and 1.5 baths.
Good luck on your birthday trip!