When a condom fails it usually does it in a way that would make you notice the failure. Condoms are made out of thin latex so when that latex is stressed during penetration and the thrusting of sex, the condom tends to rip if it fails, which is easy to notice.
Using a condom offers great protection and if you used a condom the entire time and it looked fine coming off I would not be concerned.
We generally recommend people get tested every 3-6 months if they are concerned an STI could have been passed during that period. Condoms offer great protection against STI like HIV, gonorrhea and chlamydia that are in the sexual fluids but because they don’t cover all the skin on the genitals, we still recommend getting a test every so often as STI like syphilis can pass if contact is made with an area not covered by the condom.
Let us know if this does not answer your question or if you have any other concerns or questions.