What Causes Elevated TSH Levels During Pregnancy?

I am 20 years old, female, and when I found out I was 6 weeks pregnant (this is my second pregnancy, but first one was a blighted ovum), my hair started falling out really bad. In November 2014, my doctor checked my thyroid and it came back to be a TSH of 5.76 and free T4 was 1.02. She did not check the free T3. She also checked my ferritin level and that came back to be 6. The doctor put me on 25mcg's of Levothyroxine and prescribed me iron supplements. The iron supplements are 150mg's each and I take them 2x per day with OJ to increase absorption. December 22, 2014, I had my blood work done again and TSH came back to be 3.37, free T3 was 3.42, free T4 was 1.0 and ferritin was 9.9. I was extremely happy knowing that my levels were all getting better, but I was still losing significant amounts of hair. Doctor decided to double my dose of Levo, so I started taking 50mcg's and continued taking my iron supplements. Next blood work was done on January 29, 2015 and TSH jumped to 4.84, Free T3 was 3.24, Free T4 was 1.02 and ferritin was 10.
I am now 23 weeks pregnant and taking 75mcg's of Levo and still taking my iron supplements but my question is: Why is my TSH jumping higher? Why isn't my ferritin level increasing with the amount of iron I take? & most of all, What is causing my hair loss and what can I do about it? It is absolutely devastating to me to be losing the amount of hair I am losing. I HAD such thick, strong, gorgeous hair before. My hair now is so thin I can't even tie it up, it breaks so easily. My head literally rains hair - it is constantly falling out and breaking. My fingernails don't grow and they're so weak and brittle. And also, my hair has stopped growing completely (this just happened recently- like end of December). I don't even have to shave my legs. Do you think all this is because my thyroid, my iron deficiency, pregnancy?? Will my body go back to normal after I have my baby? Give me your insights because my doctor thinks this is a total joke. I forgot to say: Since about November time (when I started Levothyroxine), I have gained 30 pounds. Last month I gained 7 pounds. I have been eating much healthier and exercising. What is the reason for all the weight gain? Is it being hypothyroid, the Levo, or the pregnancy? Thanks!