There a few issues here, if she has been on anti-androgens, for any length of time (about 6 months or less) she will be sterile. She may be able to have erections and produce prostate gland secretions but she will not have viable sperm.
A seventeen year old may have issues with Mum having a lover, and especially a MtF lover. I'm not implying that there is anything wrong BTW. But she is at an age where stuff can be very confusing, you also bring that up. She is going to have to deal with sexuality at a pretty blunt edge.
The scenario sounds weird. ' Hi I'm a woman, who wants to be a man for a temporary period to get you pregnant, and be a stepdad, then I want to be a woman again, and bring up our child as a woman but for my stepdaughter to call me by a male name.' That doesn't compute!
It is a very strange situation. I strongly suggest you and your partner seek some professional counselling.
As far as the Stepfather thing, I would suggest that this should be your daughters decision, and not your partners, or yours. Your daughter is old enough to make her own decisions, and should not be coerced into anything.
I cannot see from your post any advantage for your daughter to have a stepfather. I can see advantages for your partner to be a legal stepfather, and I suggest you think of those implications, and that of an unlikely but possible pregnancy.
