Should I even be losing weight?

I’m 65 yes old, am about 5’8” tall and weigh in the 139-143 range most of the time. I exercise a lot at a gym, before Covid, including lifting weights, kick boxing, barre classes. During Covid I’ve started walking 1-2 hrs/day because I weighed 147 as a result of quarantine indulging and not going to the gym. I have 4 children, and my weight crept up a bit with pregnancies. I had twins last and they weighed 8.5 lbs each and I gained 75 lbs, most of which I lost. I’ve always been thin (I weighed 120 when I got married 36 yes ago), and I like feeling thin. I like the way clothes look when I’m thinner. I’d like to weigh 135; that’s been my goal for awhile. This program would be perfect since losing 8 lbs would put me where I want to be. I find it very hard to lose when I get under 140. I’m doing intermittent fasting , eating between 11 am and 7 pm, no bread, no sweets, salads for lunch that have protein and olive oil/ lemon dressings and grilled meat and veg for dinner or Whole 30 entrees. Am I trying too hard?