Boobs are bigger

I'm 18 weeks and my boobs are popping out of my bra. It makes me really uncomfortable. I just don't know if I should buy a bigger regular bra or buy a maternity bra instead. My concern is that everyone says they are going to keep growing. I don't want to waste money on buying a maternity bra's and then have to buy another one down the line. I feel maternity bra's are more expensive. Should I buy a regular bra and wait until I'm almost 40 weeks to get the breastfeeding bra's.