I’ve had two embryos transferred on four occasions - a mixture of day 3 and day 5 transfers when I was aged 38 and 39. My previous three transfers (at a different clinic and at age 37) were all single day 5 transfers. With one exception, I always had top quality embryos transferred.
Like you, I initially went for single embryo transfer due to the risks associated with multiple births. Once it became clear we’d be lucky to get anything to implant, I relaxed a lot about that issue - particularly because, like you, we were worried about the cost of multiple transfers.
In the end, two of the double transfers resulted in a BFP. One ended in an ectopic and I’m now 18 weeks with a singleton pregnancy from the other. (One of the single transfers also resulted in a BFP but ended in a MMC.)
A lot depends on your clinic though - my first clinic tended to do single transfers as the default (although you could request a double transfer), while my second clinic always does double transfers if possible (although again you can request a single transfer).
To be honest, I don’t think there’s a right or wrong answer on whether you should do a single or double transfer. I have no regrets about doing double transfers since it would have taken another four transfers for me to get to this point had I done them all as singles, but I might view my decision very differently if I had ended up pregnant with twins and had suffered complications. I’d discuss it with your clinic and use their advice and your own research to make your decision.
Good luck with whatever you decide - and fingers crossed your current cycle is a success and it becomes an irrelevant question!