Can a normal brown mole that turns black with an irregular red border overnight be all of a suddden melanoma? could it be from my pregnancy hormones?

No: Moles don't generally change color overnight, although you may not have noticed before. You should see a dermatologist at your nearest convenience, or whichever physician you're seeing next. She/he can evaluate the mole and help you to navigate for a biopsy, ultimately needed for definitive evaluation.

Concerning findings: Overnight changes in moles are very rare. You are describing several changes suggestive of a melanoma...Irregular borders, asymmetric nature, multiple colors... Get that mole evaluated asap. If there is any doubt an office biopsy will shed light on what is going on. Don't delay, melanoma can be a life threatening problem, but can be cured if caught early!

Possible: Both are possible. But you should bring it to the attention of your friendly dermatologist.