Help please

So I'm 15 years old and recently I became vegetarian about 16 or so days ago. My menstrual cycle is about 30 days or so, and I haven't had PMS as bad as I used to. With that being said I could also be pregnant. But, I have had some PMS symptoms such as constipation, depression, some cramps, sore breasts, and bloating. It was the first day of my period when I had sex. I didnt use a condom, but my boyfriend always pulls out. I have never had a pregnancy scare. And I don't think I'm pregnant. Could it be because I am not consuming meat and barely any dairy. I am supposed to get my period tomorrow, and I'm starting to get cramps. Could being a vegetarian effect my cycle because I'm not consuming the hormones? Or could it ease the PMS symptoms? I looked some stuff on the internet that said it was very unlikely to get pregnant in the early days of your period, especially if you have a longer cycle. Also for PMS symptoms I do get nausea. It doesn't feel like morning sickness. If I was pregnant, I would be 4 weeks, but it is hard to say because PMS ans pregnancy have the same symptoms. I'm not fatigued, or super emotional, or having any mood swings. Which are the main symptoms in early pregnancy. But also some women don't have any symptoms in early pregnancy. Overall. I don't think I'm pregnant, but I would like someone who went through the same thing as me to give me some insight. And I'm 29 days into my cycle. Please comment :)