I too am considering the decision of one day having a baby naturally and am torn. However 'wanting' a baby isn't a good enough reason to have one in my opinion, the possibilities of endangering your relationship, you baby and yourself are more important things to consider than simply 'really wanting' a baby. Some things we want and we shouldn't have. People with diabetes sure as hell want sugary sweets but because it's not safe for them they don't have them.
It sounds like you need to become stable before even thinking about adding another thing to your plate and I agree with your partner on this one. He is looking out for your best interests, his best interests, a possible child's best interests and your relationship's best interest and so should you. Given though, it sounds like he might not be putting it in the nicest way, but sometimes this type of stuff needs blunt honesty over sugar-coating.
It took me over 6 years of concentrating on myself to find stability within my bipolar, it took many drugs, a **** load of therapy and a huge amount of support and understanding from my family to get to this point. All I can say is that it was hell, and much like you I wanted something I wasn't ready to have. I was removed from University studies 4 times in those years by my medical team because I wasn't stable enough to continue, but I was lucky they saw what I couldn't when I was amongst it all. You need to admit that your illness is a huge pain in your arse that you need to slowly get a handle on and that has to be your top priority, if it isn't then there is no way you'll ever get even close to the things you want and you will no doubt lose what you already have in the process of denial. Believe me, I lost a lot and I don't want you to do the same.
Get your own individual arse in therapy, go through the horrible ******** of finding the right meds for you (this takes a long time) and begin your journey to stability. I'm here and I'm sure I won't always be here (it's never cured, that's for sure) but I'm finally able to look at those big decisions from this point in my life. I want you to be able to do that one day too.
Gen x