Hi
I am also a similar age and weight to you and I went on a big diet starting in December and have lost 30 pounds. I recently bought a whole new wardrobe and I was so excited to fit into a smaller size - and then I hit a wall. It happens. It has happened to me before - the key is not to let it dissuade you and I do not think you should resort to tablets. As long as you are not putting on weight, it is OK to stay the same for a while. In theory it is easier in the summer to motivate yourself to lose weight but you can get complacent, everyone telling you how great you look.
Try a new incentive to get you through the next stage. I bought a dress for a friends wedding in October - which fits but is too tight, but i love it. I know i need to loose another 10 pounds before her wedding - that is my goal.
The problem with diet pills is that you come off them and it all goes back to how it was before. Be strong, do it yourself, there are no quick fixes and you will feel so much better for it!
Good luck!