Ugh. Worried about getting pregnant.

Okay, my husband and I have been married for 4 years and have a 2 year old. I am not ready to have another one. We use condoms sometimes, but my body/cycles are like clock work, so I know when I'm ovulating. My cycles have been 24-25 days the past 4-5 months. Today is day 7 of my cycle (I just finished my period on day 5). We had unprotected sex tonight. I'm so afraid I'm going to ovulate early and the sperm will still be living inside. :( advice please :(