Should I go lower

If you can, get dexa body scan to determine how much body fat % you still have.  If you are low - losing more weight would mean losing muscle and bone mass. 

Sometimes it via better for us to be heavier but have more muscles. Not only that would help us maintain our weight but it makes us stronger. 

Getting too low may cause some health issues. 

The younger you are - the low body fat% can be OK without affecting you health. 

I was older, but when my body fat % dropped below 15% I went into instant menapouse... And I had other issues... 

This is a great point. It is possible to be a type of skinnyfat- where you are at a normal or even low bmi, but still have a lot of fat packed around your organs. The scan would help to determine what the best level is for you. In my case, I have a bmi of 22.5 at the moment, but I would be willing to bet a year's salary that my bodyfat percentage is relatively high. Your health depends on more than just the weight number in other words. 

I'm 5'4 and need to be at 125, so you've got a long ways to go at 5'2.  140 is too heavy. 

Ok, I will go lower, I just don't want to look like skin and bones

I struggle with the number on the scale! I am currently 16 months post op and am 5'11" and weigh 184. I hit my personal goal of 178 last July and have gained 6 pounds and most of that is muscle. I work out 4-6 times a week. I had zero muscle when I weight 178. I continue to weigh myself daily and the scale is in my head. I look better at 184 than I did at 178, certainly healthier. I agree that it is difficult to come up with that ideal number. I am trying to let my body decide, easier said than done.

I am also 5'11". I had a dexa scan done 6 months ago which really helped with figuring out what was reasonable for me. it is on my blog if you are interested... When you are taller I think it is even harder to figure out. body fat testing

I've never heard your surgeon's reason for staying at a higher weight. I thought the research suggested lower weights are associated with longevity but I might have that wrong. 

Nevertheless, I'm 5'2" and maintaining at just under 115. My goal was 125 but I drifted down in maintenance and have prettily easily stayed there for almost 3 years. Pics in my profile show me at that weight.  All medical professionals are very pleased I'm at this weight and a DEXA scan indicated my body fat is at the low end of normal for my age (59). If I was younger I could have gone even lower. I felt really skinny when my weight first dropped this low but now I feel just right. It takes time to adapt to being truly slim. 

I would go lower. Statistically you are likely to regain 5% of what you lost. Give yourself some cushion for sure. 

Ok

I am 6' and was 167 before getting pregnant. My goal was 160/size 12, then to regain some muscle and ultimately end up still a 12 but probably more like 165-170.  I've lost a lot of muscle since surgery. My numbers may be a little low depending on how others are built, but for my frame it's good...my entire family is tall and skinny and I have no hops/butt.