Deciding to move on to ivf

Hi ladies. I have infertility due to a Hashimoto's thyroiditis and we have been ttc  for 16 months, 9 months of that at the RE. I have had three cycles of clomid and got pregnant on two of them (one natura and one iui) but miscarried both, one at 9 weeks due to chromosomal abnormalities and the most recent at 4 weeks either due to the hashimotos or an immature follicle.  Our RE recommended two more cycles of iui and if not pregnant move on to ivf. I've already started this cycle and am on clomid but am really considering just going for ivf next cycle instead.  How did you ladies know when to move on to ivf? Or should I just do the iui first? Thankfully cost isn't a factor as we've been saving for a house for years and can use that money for ivf instead.