IVF newbie, Thyroid, and Prolactin

A little background: I've done 6 rounds of Clomid & 2 rounds of Femara (2 IUIs within these cycles). I responded well on all medications, always ovulated, had a 15-16LP each cycle, great uterine lining on all cycles, etc. My HSG was normal and my husband's semen analysis was normal. I, however, have been battling hypothyroid and elevated prolactin. In January of this year, my TSH was 5.9 and my prolactin was 37. I was put on 50mcg of Synthroid.

I switched RE's and my new RE and I decided IVF was the next choice of action. IVF (3 rounds a year) is thankfully 100% covered for me. My new RE ran a blood panel. My TSH is now 2.4, my Prolactin is borderline elevated at 26.3, and I was Vitamin D deficient.

I had the above blood panels done on 4dpo, so just after ovulation. My RE wants to recheck my prolactin this week, as my period just started yesterday. I'm being tested in the morning after fasting.

Why do I have to fast? Does ovulation cause prolactin to elevate? Should my thyroid meds me increased?

I'm worried sick about elevated prolactin and pituitary tumors...

IVF newbie, Thyroid, and Prolactin