It may or may not be possible to lose it all by May and as far as I know there's no real way to predict that. To get to 140 by May 1st, you'd have to lose 2 pounds a week, every week. Average is 1-2 pounds a week. I lost a lot faster than that at first, but I've really slowed down now. I think most people do when they get closer to their goals.
BUT, even if you don't get quite to 140 by May, you can still lose quite a lot between now and then and really improve your health and your self esteem and appearance. One thing to keep in mind is that even if you don't get all the way to your goal by your trip to Paris, you will still look and feel better than if you don't lose anything at all. Right?
I agree with the above poster that it might be helpful for you to set a smaller goal to keep in mind now. That's what I've done and it has really helped me. I know a lot of the women here have "long term goals" and "short term goals." I personally find it helpful to have a "time limit" on my short term goal, because it keeps me motivated. But I don't have a set limit for my ultimate goal weight. I'll get there when I get there.
I really think you can lose quite a bit between now and then if you stay on track. Are you keeping track of your calories at all? There are several places online that you can track calories, or you can just write them down on paper. I use
http://www.fitday.com/ for my calories. That might be helpful for you too. There is so much support here, I'm sure you'll find that this board helps you to get to your goal.