My pregnancy is becoming unbearable and I'm only 15 weeks and 4 days. I always feel dizzy/light headed, weak, and…

My pregnancy is becoming unbearable and I'm only 15 weeks and 4 days. I always feel dizzy/light headed, weak, and sometimes have blurry/shakey vision, and get headaches almost everyday and they can last anywhere from minutes to all day. I get 8-10 hours of sleep every night, I take my prenatals, I eat 3 medium sized meals and 2 snacks a day, and drink water throughout the day. My last pregnancy was nowhere near as bad as this but because I knew every pregnancy was different, I've been brushing it off for a month or two. But it's becoming so bad it affects me taking care of my daughter and cooking and cleaning. Even as a nurse, I don't know what's going on. I'm eating enough, drinking enough, and sleeping enough. Anyone else know what's going on?