4+ weeks preg and lower backache

Hi, I found out I'm pregnant after 15 months of trying. I'm shocked and also scared. The next option was IVF so honestly I need to pinch myself to believe I got pregnant naturally. I had endometriosis, blocked fallopian tube, low AMH and my husband had low motility. But here we are ✨ But I'm getting lower backache cramps. Is it normal? I also get little vaginal discharge. Is that normal too? No blood at all... I'm just worried !