No heartbeat at 7 weeks, 5 days ultrasound

I had my first ultrasound on Thursday, and they couldn't find a heartbeat. Everything else was present and measuring on schedule, so my doctor figures the heartbeat stopped within a day or so of our appointment. They prescribed medication to induce a miscarriage, which I took yesterday. I was very nervous about the pain, but they also prescribed Tylenol 3, and with that, it was manageable.

So today I'm just sad. This was our third FET, after our first two failed. I thought this was it, right on average, with the third FET working out. It'll be four years of trying next month, and another sad Christmas/New Years is in store. Especially because this year my BIL and SIL are pregnant; it's going to be hard to be around them over the holidays.

I'm wondering what my next steps should be... do I request the same protocol again, because "it worked" (until it didn't)? We did a modified natural FET with letrozole, and two intralipid infusions (one before the FET, and one after the first positive beta). It was a tested euploid 5-day embryo.

Any words of wisdom, or hope?