Here's some info from the past. I used a diaphragm with a spermacide for years. It can be left in for hours prior to having intercourse. Use more spermacide if it's been in a day or more and you don't want to take it out. I think it has to be left in for an extended period after intercourse. It's not as effective as several others but it's still listed as moderately effective in the charts.
At the time my gyn said that if I'd faithfully used both the diaphragm and the spermacide the odds against pregnancy were nearly as good as the pill. I didn't get pregnant but that proves nothing. You could at least use something like this until you decide more definitely on something.
Another use for the diaphragm is to temporarily stop the flow during your period. Really handy at times. lol
I would also recommend the patch as a temporary measure if you want to continue considering more permanent options. You might like it and it's not expensive like the rings and the IUD and you can stop using it at any time.
My daughter had an IUD with no hormones but she cut off the string so short she couldn't feel if it was still in place. She ended up with a tubal pregnancy and was told that the incidences of tubal pregnancies is higher with this IUD. Other than the tubal pregnancy she liked it. And the fact that apparently she lost it.
All bc requires consistency, even the IUD which can dislodge so it's placement needs to be checked regularly.
She has told me that her body reacted differently to forms of hormonal bc after her first pregnancy. Which suggests that you could try one of the previous ones that was unsatisfactory before. Also I think their are pills that contain less hormone than they did 5 years ago.
You might try telling your stubborn man that a larger size condom means he's larger. lol or is he not macho in that way?