Why are they telling me not to lose anymore weight?

At 16, I was 135lbs (67.5" tall) and in a size 6/7. During my senior year, I gained 15 lbs from a slow in sports and stress. After graduation, I moved out, got a job, got my house and stopped doing any activities and discovered cheap fast food. My weight jump to 200lbs and then I discovered I was pregnant. Thankfully, I only gained 15lbs and lost all 15lbs at delivery. After a year I had only lost 15 lbs, and then another year went by and I lost another 15 lbs (170lbs). This past winter, my weight went back up to 182. In February, my workplace offered free wellness coaching (not a certified nutritionist FYI) for employees to instill good diet/exercise options. I got every week for about 15 min to talk about my eating/exercise plans. Since then I have lost 30lbs (in 14 weeks) and I'm finally down to 152 (size 10 in jeans from a 14). I still want to lose another 10-12 lbs, but my coach is telling me not to lose anymore and to keep my weight where it is. I'm happy with my success, but I still want to aim just a little lower with my weight. to about 140-145. I have been working really hard to get where I am and I feel like I can do it! What's the problem? I'm thinner, yes, but I just there are still a couple of problem areas (inner thighs and lower back) that I want to work on and lose the fat around them. I have been eating well and exercising about 3-4 days/week. No crash diet or anything. Why do they want me to stop? I don't look sickly or anything. I mean, how can you looks sickly when your 152lbs? Should I not listen and just aim for my ultimate goal or just stay where I am just because she said so?