I have a terrible problem...?

I drive a friend of mine to work mon-fri and I have been feeding a stray cat (sweet as can be) I drive 18 miles just to get to her house...then another 5 to get to work...I noticed today that the cat is pregnant and I dont want her to have the babies in that area (bad area) but I am willing to catch her and bring her to my vet to have her checked out ( I am wary of bringing her in because of my own cats until im sure she doesnt have any diseases) I can pick her up sat or sun in the morning but what do I do once I get her home when the vets arent open until monday Im too scared to bring her home until Im sure she is ok and she only comes out in the mornings for me to feed her I never see her in the afternoon when I drop my friend off...Im so worried about her she is so sweet...Help Please!!!