IUI versus IVF

Both my partner and I just turned 40 and are getting desperate for a second child. We have had one viable pregnancy which is now our lovely three-year old but this secondary fertility "journey" is really getting me down. I've had one MMC (2019, age 36) and then a chemical pregnancy/miscarriage in March (2023, age 39) this year. Just finished our second round of IUI (while on Ontario, Canada government waitlist for IVF). So discouraged - taking some supplements/vitamins, trying to eat well and exercise but I really need some hope here. Is IUI even a good use of money/time/energy at this point or should we just go straight to IVF? Any advice, suggestions and/or resources would be appreciated! Thanks for your time.