How do you know when to stop?

I am 38yo. I have been intermittently ttc for about 7 years, but the first 3 probably don't count because I was too big to get pregnant. Then the next 2 don't count because I had bariatric surgery and was on birth control for 18 months (dangerous to get pregnant right aftet surgery). Well, I lost 165 lbs., started ovulating regularly, and hoped things would work when we started trying again after stopping birth control and losing all the weight. Tried for about a year before going to RE. First round of IUI with letrazole was successful, but miscarried at 9 weeks. Since the miscarriage, 2 more letrazole IUI cycles and 6 injectable IUI cycles. I never would have originally done this many IUI cycles, but the first one was successful, so I know it can work, but I am exhausted. I don't really have time to take a break from ttc given my age. IVF is not really an option. Insurance covers very little for IVF, but covers most of IUI (We end up paying about $300 a month). My question is when do I give up and call it quits? At what point do I have to accept that I won't be a mom? It is so hard because it was so easy the first round. In many ways, I wish it never worked at all. It would make this so much easier, but because it did work, it is so hard to not keep thinking that just one more time and it will work again.