Everyones breasts do different things during pregnancy so I can't say when yours will stop growing. Mine didn't really get any larger after about 20 weeks until my milk came in. Hopefully you will stay where you are for the next few months.

I found that the DFO and Trade Secret have good brand maternity bras for good prices. I don't know where you are so don't know if that helps. Also some of the really firm sport crop tops are good when pregnant as you don't need the clip straps yet. Just normal soft cup bras can be much cheaper than maternity bras too so might be an option before bub is born.

I wore my E cup bras right through being an F and then when I was a G cup after my milk came in and they were fine. As long as they are the nanna style ones that you can't really spill out of... the super firm fit felt good on super engorged boobs too. I did have to get a couple of new E cup bras after my boobs settled again though as the original ones were stretched, but I had gotten about 6 months wear out of them by then. I have mostly lovable bras as they are quite generous in their sizing and fairly affordable.