I understand you are asking about signs that this cat is pregnant...however, there are many groups that will provide low cost if not free spaying:
Texas state Animal Friendly Account
Contact the Fund for Animals 713-862-3863 for information about low cost spay/neuter available through the state's animal friendly car license plate fund.
Animal Defense League
11300 Nacogdoches Road
San Antonio, TX 78217
Free spay/neuter for pets of low-income people.
Spay Neuter Your Pet (SNYP)
PO Box 29435
Dallas, TX 75229
Discount certificates for pet spay/neuter in the Dallas-Fort Worth area.
Luv A Pet S/N CLinic South Oak Cliff Dallas TX
HSUS Spay - Neuter Clinic/Animal Wellness Center
4830 Village Fair Drive
SPCA of Texas
Martin Spay/Neuter Clinic
214-651-9611 ext 116 or 133
Low cost spay/neuter. Also, for pets of qualified low income people, there are low cost veterinary services.
Brown County Humane Society
Brownwood TX 76801
Has a drawing to provide very low cost spay or neuter for 15 animals per month.
Animal Birth Control Clinic
Animal Aid Humane Society
1531 Wooded Acres Drive
Waco, TX 76710
Waco Humane Society
254-399-9883 or 254-754-1454
Low cost or free spay/neuter for low income.
Fund for Animals
1603 Shepherd Drive
Humane Society of Southeast Texas
2050 Spindletop Rd
Beaumont TX 77705
Spay/neuter assistance certificates offered to all who want to spay/neuter a dog or cat. Certificates for low cost s/n for feral cats also available.
Life Force Operation Spay
148 South Dowlen Road
Beaumont, TX 77707
"We welcome all low income, elderly folks and anyone not being able to afford the full price" of spay/neuter of pets.
Williamson County Humane Society
Cedar Park/Leander TX
Animana Birth Control Vet Center
Animal Trustees of Austin
5129 Cameron Road
Austin, TX 78723
Low cost spay/neuter and vaccinations.
Emancipet mobile clinic
Homeless Pet Placement League
PO Box 273027
Houston, TX 77277
Free spay/neuter for pets of qualified low income people.
Houston Humane Society S/N Clinic
14700 Almeda Road
Houston, TX 77053
900 Portway Drive
713-869-7722 ext 136
Free spay/neuter and vaccinations for qualified low income.
Spay/Neuter Assistance Program (SNAP)
PO Box 440304
Houston, TX 77244
Mobile clinic goes to low income neighborhoods and provides free spay/neuter and vaccinations to pets for qualified low income.
Long Drive Dog & Cat Hospital
Spay/Neuter Assictance Program II (SNAP II) - See above
San Antonio, TX
Humane Society of North Texas
1840 East Lancaster
Fort Worth, TX 76103
Low cost spay/neuter for qualified low income.
North Texas Spay Neuter Coalition
Denton Low Cost Pet Sterilization and Vaccination Program
If you contact these groups and tell them about your situation..they may be able to cover the fee and then you wouldn't have to worry about her being pregnant or becoming pregnant.