Maternity bras need advice!

Tomorrow I'll be 16 weeks pregnant and I desperately need to buy new bras as the ones I have are barely fitting anymore. This is my first pregnancy, and I am completely confused on what type of bra I should be purchasing. How do I know which size to get (especially if I want to purchase online)? Am I expected to purchase more than one size as my size changes over the months? Also are nursing bras okay to wear now so I won't have to buy new bras all over again? I would love for any advice especially for recommendations on brands you've tried. I'm just looking for basic everyday bras to wear throughout my pregnancy. Thank you in advance!