Just thought I'd share some of my own experiences with things that you are concerned about, in the hopes that they give you some kind of useful ideas.
I struggle with depression and often cope by overeating; that's what's pushed me into the obese category. Family members who are physicians have suggested medicine for the depression in the past and while I didn't take it, I do wish now that I had. Exercise has actually helped a great deal with reducing the depression to manageable levels -- and also aided my weigh loss goals. I encourage you to try the medicine your doctor recommends and try to push yourself to exercise a bit. It might sound odious, but even just doing 15 minutes a day for a week and then building up in 15 minute increments in the next week's routine, helps. It helped me, though some days, making time to exercise or finding the energy feels hard. Having only recently emerged from the lowest of the depression, I've been re-evaluating the things that brought me to this point, in both body and mind. In many ways, I felt isolated and like I had no help in my life. Medicine seemed to come with stigma and seemed like a shortcut that I didn't trust, so I avoided it. But, body and mind are connected. I realize, now, that if I had taken the medicine, I could have been able to find a way out of my depression 3 years ago instead of now (and maybe not gained so much weight, too). I felt like I just lost 3 years and woke up out of it and if I could do it again, I'd have taken the advice.
About phentermine, I can only offer you my personal experience with it. I struggled with weight loss a great deal and it took extreme exercise to get my fat to budge at all, effort that I often didn't have the energy for. After years of suggestions, I finally decided to try the phentermine and have been taking it for 3 weeks. It's helped me so far and I've lost a total of 16 pounds, at least 10 in three weeks, thanks to the phentermine. It does make me a little emotional toward the end of the evening and a little jittery, but it gave me the energy and the emotional boost I needed to get into exercise and serious dieting. It helps with the emotional eating by suppressing the appetite, I think. I was surprised to find that taking St Johns Wort (suggested as an alternative to prescription meds in my case) and Vitamins and taking the phentermine have felt like the supportive boost I needed to feel less isolated and defeated by the struggle.
Anyway, once you start losing some weight and exercising a little, hopefully both your weight and your mood will improve and the cycle will be a happier one.
I struggle with this a lot, but I'm finding some positivity. Hang in there and don't give up! You're not alone in this and you're being strong just by considering options and making an effort.