You could buy a cheap breathalyzer on Amazon for under $10. While mine only seems to show ketosis when I have been fasting or been really limiting carbs (no nuts, no cheese, no berries, which is rare) it may work better for you and is not a big investment.
I agree with some of the posters that bariatric surgery may not be an answer without having overcome snacking especially if you have some eating issues that are not purely related to eating. Also, unless you are extremely short or have a severe health challenge or other medical reason , and I admit this is my prejudice, I do not see you at 220 as needing surgery.
I have been keto since April and only lose on longer fasts. Then I lose about .5 lbs a day. I do not weigh myself during, usually the morning after I eat again or 36 after I eat. Then whatever I weigh then seems to stay with keto.
It also really helps in terms of sticking to Keto when out. I know that if I need to skip a meal I can. I am never starving and can now even sit and watch other people eat and not participate although I will have coffee with either half and half or I prefer cream. It also takes away the opportunity experience excuse of eating. What I mean by that is perviously, if it was special occasion (not a very special one but more of an ordinary special occasion, like we happen to be at a nice restaurant that served a food I love) I would use that as an excuse to break my diet, I will not get this chance again to sample this, let me resume my diet tomorrow and of course 3 weeks and 10 lbs later I would start again. I do not anymore. I stick to keto all the time or try to, I am sure there are sauces that I have eaten that have more sugar than I would make but it does not seem to matter. I just came back from an out of town visit with family and every dinner was eaten out. I did have some nuts and cheese with me but would have managed fine without them and ended up leaving the cheese there and bringing back about 25% of the nuts. I gained a lb total which is a normal fluctuation.
The longer fasts help me so much with snacking because I get used to not mindlessly eating something whenever I go into the kitchen. When my urge to snack returns I know it is time to go on another fast (3-5.5 days). I do HWC in my coffee, water, broth on the first day or so with shiritaki noodles if I am really hungry. I have started feasting a couple of days before a fast. Only extra fats, including fun fats like sour cream, but no chocolate (which I never have) or artificial sweentners (which I only have when making keto pancakes once a month or when have gross coffee out of the house, also rare).
If you have nuts have you checked to make sure they are lower carb some are higher carb than you think.
Your labs look ok to me but no expert. Do you have trouble waking up in the morning and going to sleep at night based on cortisol?