Conflicted on transferring 1 or 2

Crystal • 4 failed IUIs before Fresh IVF cycle July 2016 which resulted in my 3 year old daughter. FET Jan 2018 resulted in miscarriage. August FET #2 & October #3 & January #4 failed. Round 2 of IVF June 2019 failed. Surprise natural BFP Nov 2019🤞

I've posted this on another board as well so sorry if repeated. I gave birth to my daughter in 2016 after my first successful fresh transfer. This past year I've tried 3 FETs for #2. First ended in missed miscarriage and other 2 failed. Lining and labs have always been good. No PGS testing so RE thinks it's just poor quality embryos despite good grading. I have a 3BB and early blast left and I'm praying to not have to do another retrieval. They are willing to transfer 2 which I initially was agreeable to. DH are sure we do NOT want twins but also want to increase our chances. I'm currently rethinking transfering 2 due to risk of twins but I also want the best chances of having #2. Any advice or suggestions? TIA