Welcome! This board is great; you'll find plenty of support, motivation, and inspiration within.
I'm currently on a journey to lose 142 lbs. It hasn't been super-quick for me, but I also don't have the most typical weight loss timeline.
I was 277 lbs right before I got pregnant with my daughter in September of 2011. I was diagnosed with gestational diabetes very early, and therefore was forced to completely change my eating habits. I weighed 269 on the day I gave birth, so even though I wasn't really dieting during my pregnancy, I was still losing fat as I "gained" a baby.
I took a bit of a break from healthy eating right after she was born (since I could actually eat carbs again), but started using my fitness pal on September 1st. Since then, I've lost another 50 lbs. I'm hoping to be at goal (another 60 lbs) by the end of this year.
Anyway, I think that losing 127 lbs in 14-15 months is doable, but try not to get hung up on a specific timeframe. As others have mentioned, mini-goals are a huge motivator for those of us who feel like it is a never ending journey.
Working out often will be key, so kudos to you for already joining a gym (especially one that makes you feel comfortable)! I recently joined a gym myself, and my weight loss has been greatly enhanced. Since early January, I've also cut out sweets and make a very conscious effort to spend my calories (I eat 1200/day and log my food using the My Fitness Pal app) on the "right" kind of food: veggies, fruits, lean meats, whole grains, very little dairy.
Also, I usually take a free day each week so I don't totally burn out on dieting. The interesting thing is that I used to take free days that were totally ridiculous -- pretty much a "how much bad crap can I stuff myself with, since this is my only chance" sort of thing. At this point, my free days are really more of a free meal. I still work out, log my food throughout the day, and eat all of my fruits and veggies, but will maybe go out for dinner or have a glass of wine and dessert.
Yikes, I'm long-winded. Anyway, welcome! We're glad to have you!