I was having unprotected sex with my ex partner for a year and six months I only saw him 2-3 times a week sometimes more sometimes less. I never fell pregnant he then got with another girl and got her pregnant within months. I've had unprotected sex with 2-3 people once unprotected and nothing's happened. I'm now in a relationship it's been 4-5 months and nothing's happened. Do you think there is a problem?