IUI vs IVF

So I’ve just had my 3rd miscarriage since January 😫😭 I’m bleeding as I write this 😞I have 4 kids from a previous marriage and have a 15 month old with my current husband. I never anticipated having SO many issues getting pregnant this time around..I’ve had 6 miscarriages in 3 years. I just turned 40 and my husband and I REALLY want another baby..his insurance doesn’t cover infertility. We made an appointment to see a specialist but my question is does IVF sound like something we might have to do? I don’t seem to have an issue getting pregnant it’s just a matter of sustaining the pregnancies at this point. What is the difference between the two?? Thank you for any info🙏