Hi and welcome. The short answer is that if you were only interested in a single woman for an FMF/FFM you would substantially reduce the number of single women available to you here, because like me many of us are uninterested in unicorn hunters. If you are also sincerely open to couples as well, that will definitely increase your chances of finding compatible playmates for threesomes and foursomes.
As far as your profile, it could use a little work, but it's a really good first effort (which sounds but isn't meant to be patronizing). I like how appealing it makes you sound, so I'm not going to suggest any wholesale changes. I'm even going to ignore things that I'd normally suggest you change, because I think it works better for your age bracket and what you're trying to find than something smoother would.
However, you have to remove the emojis. Every last one of them. The only reason you get to keep the exclamation marks is that you're young. ;-)
In the description of her, remove "physically" and the quotation marks. In the description of him, it's quick witted, remove his height (it's elsewhere) and then seriously consider adding something about things you like to do, individually and as a couple. I know that as young parents you don't have a ton of time, but it helps to flesh out how you're being perceived.
Fantasies is good, although the answer is me. I'm happy to be a third, or one of three singles, but for some reason I have zero interest in FMFs as part of a couple. If I hadn't already used my one allowable emoji, I'd use one here.
In Additional comments, I would remove this: "We've decided to try...the fact that" and just start at "We are both confident..." You'll just need to add a "which" in to make the sentence scan better.
And please, please, please remove those two ending paragraphs. Your permission isn't needed, you will not be bringing legal action, and it's a kind of alligator in the sewer myth anyway. Also, it's an eyeroller, plus a terrible way to end your profile.
And that's all I have. Good luck. Except that the last thing that will attract a single woman is a picture of another woman's body parts. The two of you together, looking all happy and stuff? That will work way better.

