Many years ago, my husband and I flew from California to Baltimore with our 14-month-old twins. The traveling part was a long nightmare because we had to drive 2.5 hours to San Francisco, stay overnight in a park-and-fly hotel, get up before dawn the next morning, transfer in Denver, - the flight took all day from before dawn to landing in Baltimore at 11:00 pm. Sort of comparable to a flight to Europe. Here are my travel tips:
Before we flew, I purchased a pretty sturdy stroller at a second hand store, because our stay-at-home stroller was a very nice one, and I didn't want it to get banged up in the plane's baggage compartment. Somehow after our flight, the stroller was right at our fingertips as the flight attendant or someone rushed down to get it for us. Can't remember if we paid extra for it, but I don't think we did. We did have to pay extra for the rental car to have twin car seats, and we had to set them up ourselves the next morning at the car-rental place.
Thank heavens we had the foresight to book a hotel right at BWI, our destination, so we all fell into bed with exhaustion. Very glad that we didn't have to drive further, as we were exhausted from the flight. The twins during the flight were like little baby panthers, and husband and I had scratches all over our necks from them clawing to get out of our laps. We bought alcohol for the two people in front of us. who were very very nice, saying no worries, they were parents also. The twins NEVER SLEPT during the flight. We starved because we thought we could eat on the plane - but the children made that impossible. Lucky for you - with just one baby you can take turns eating!
We took along BRAND NEW TOYS that the kids had never seen before, so that they would be mezmerized, and that did help. Nowadays, your ipad mini can play Teletubby videos or Baby Mozart, and you could even see if your baby would wear a little headset. A plane is a very loud place, and I wish I had this trick back in the late 90s, to both entertain them and protect their hearing. Now I always fly with ear protection.
Our carry on bags consisted only of baby stuff - not our belongings; but it was also the time before the 3-1-1 quart bag rules. It was snowy winter back east, but we had LL Bean ski suits for the children, which we used every day, plus parkas and pull-on boots. May in Paris can be in the 50s, which is not warm, and can feel cold if the wind is blowing. Taking layers of clothing is a good idea for the tot. Jacket with hood is a good idea.
My children scratched out one of my small gold earrings in the plane, which I never found again, so don't wear any jewelry. Is your baby eating little treats? Take plenty of treats on the flight. Try to have the baby drinking something during take-off; the swallowing will help with the ears popping.
Keep a little umbrella stroller in your car for the trip home. At the European airport, if the sturdy second-hand stroller is really banged up, maybe you can leave it with someone instead of taking it home, and just walk through the airport and customs with her in your baby backpack.
Good luck and have fun!