Ovulation

Okay so me and boyfriend always have sex with a condom but lately he’s been asking me if we can try it without one but I’m scared I’m going to get pregnant so I keep saying no. But I really want to do it without a condom too but how can I ensure that I won’t get pregnant? I use the period tracker and see when I’m ovulating but im scared that even if it says I’m not ovulating I’ll still get pregnant. What should I do???