I think everything is inside the title. According to you, is there a spirit that could worked perfectly to assist me conceiving a child with my girlfried. As we are not living together, we have to meet during the right time of the month to conceive. I would really appreciate the assistance of a demon, or anytime of spirit that works well and fast in this domain.
Is there one you have used ?
I suggest avoiding demons for this, they’re not the answer for everything - there are fertility gods and goddesses in every pantheon, and they would be by far the best choice since their names became well know for answering prayers and rituals for this purpose.
Hathor & Taweret from the Egyptian panthoen are excellent, or literally any other, including from the Americas, all have fertility gods and other deities who guard over pregnancy and birth, it used to be far more dangerous so it was a big aspect of religion and magick.
There are also saints for this, that would be something to search on google. But personally I suggest avoiding demons, that’s not the kind of thing you want them getting their claws into. IMO.
Demeter and Persephone.
Did you manage to find a ritual/ spirit?