I miss my mom??

My parents are currently out of town on vacation and I just realized that I really miss my mom? It’s been the first time in two days since I really thought about missing her but I just started crying because of it? I’m on the last day of my period so I thought that might have something to do with it but my cycle scope said I should be feeling confident (I know it’s not super accurate but still). I’m just really sad and I feel like I’ve been taking her for granted my whole life now that she’s not right down the hall. She’ll back in two days but I still feel really sad. We FaceTimed earlier today but the sadness hadn’t really kicked in yet so I didn’t say much and I feel really bad. This has never happened to me when she has gone on trips before (I’m 15). Is this normal?