Friendly stray cat needs spaying at a cheap cost

Hello guys, this is a female kitten that I have been feeding since birth but not allowed to adopt due to my strict parents. Lately she has been meowing weird and I saw her with male cats often. I figured she has gotten into heat but I'm not happy about it. She is only 7-8 months old and she is small. I'm afraid if she gets pregnant it will be very difficult for her if not life threatening. I contacted a local vet and they quoted 5.5k for the surgery. I cannot afford that much money as my parents aren't showing much support. They are of the opinion that it's natural for cats to do this and to let it go. But I'm not able to do that since I have grown attached to her over time and knowing she is suffering / will suffer breaks my heart. Please suggest any NGOs or local vet's contact details (I called blue cross but I couldn't get past their automated message) who can do spaying services for CHEAP. Thanks!