Sweetie... take it from me. NOW is the time. You are so young, and you have so many happy years ahead of you (hopefully with babies
) Believe me, you will enjoy babies sooo much more if you are at a healthy weight.
I am 35 years old... and around the same size as you. I was approx... in the 220's when I had my baby (I was 21). I loved her so much, but at the same time, it was really hard.... harder than it should have been. One of the worst parts for me was not fitting into those little itty bitty kiddy rides that we all love to take our kids to. They can't ride those alone when they are little... and believe me... it's not the same letting them ride with someone else.
Get yourself healthy... you CAN do it. It's not easy, but it will be so worth it when you can do anything and everything that you want to do with ease.
Good luck to you!!!