When to change your weight loss goal

HI All!
Looking for some advice.
My story is this:

June 1, 2016 weighed 238lbs, height 5'4" and started using mfp and gradually increasing my exercise. Started with a 2lb/week loss and now at 1lb/week loss as 1200 cals/day was not feasible for me. I am set at lightly active as I am an emergency room RN and work 12 hour shifts (I work part time) and also have a small farm that my husband and I do a market garden on. Some days I am less active than others as I have a chronic back injury that flares up from time to time. I have started doing yoga at home and finished the C25K program and run 20-30 minutes about 3 times per week and I walk usually 7500-15000 steps per day. I eat most or all of my exercise calories back (from my samsung gear fit 2) but don't usually add in things I consider regular exercise unless a significant amount is done (i.e. gardening). I used to be a mindless snacker, especially in the evenings, and have drastically reduced snacking. I drink tea instead, run or walk in the evenings, and really try to listen to my body as to "am I really hungry or bored". I use a food scale and measure liquids most of the time but not always. We eat out about once per week, usually sushi.

Today my current weight is 164lbs. I feel great! Still have a chronic back problem but am better managing it without drugs. My goal weight is not really a set number, I am thinking 135lbs but I haven't been lower than my current weight for 15-20 years (I am 41 years old now). I used to weigh 110-120 lbs in high school and my early 20s. I carry most of my weight in my abdomen/hips/thighs.

I currently have my goals set to 1 lb/week loss with a daily calorie intake of 1450 before exercise. I am wondering at what point I should decrease my weight loss goal. I understand it will be more difficult to lose as I get closer to my goal/my BMI for my height. I lost 5 lbs in the last 6 weeks and am definitely more active at the moment as we are gearing up to plant our 2 acre garden and doing spring cleaning/yard work. I don't want to lose too fast as I want to be healthy and make it sustainable. I have noticed that I am hungrier in the last few weeks, probably due to the increase in activity, but my loss has not changed based on my calories in/calories out.

Thanks in advance for any advice given
Cheers Jen