I'm hating life right now 😞

Cassie • Currently pregnant and I have an amazing 9 year old daughter!!!
So, I'm not exactly sure how far I am due to an irregular cycle. I did take a pregnancy test that showed how many weeks you are and it came back positive and said 1-2 weeks pregnant. I tested 2 Thursday's ago, then I made a doctors appointment that following Tuesday. Due to my previous pregnancy ending on March 13th this year, my doctor ordered me to have blood work done. He said it would be good, because we weren't sure how far I was and to track my Hcg levels. So the first time I tested was on 9/22 and my Hcg level was at 50.7, second time was on 9/29 and it was at 337, and this current one was on 10/5 and it was at a 443.4. My doctor said that it was very low. So now he ordered another test for tomorrow. Should I be concerned? Did anyone experience anything like this? Is it low for 4-5 weeks, should I worry? I really want this baby and this month was the month that I was due with the last miscarry, so me finding out I got pregnant again made things a little easier to cope with. I would be devestated if I lost this baby, especially this month. I'm really down in the dumps about all of this. What is a common Hcg level around 4-5 weeks? Please help!