stock pile

is it too early for me to start a stock pile of diapers and formula? I'm 7weeks and I miscarried last pregnancy at 10 weeks. I'm praying this baby sticks !& When it's time for birth im afraid I won't have as much money as I do now.. I am planning on breatfeeding but with my first born in the NICU my supply went low in 3 months! I'm due in August and know for sure I will reliever preterm again (because I'm small) So I want to start a stock pile with formula & diapers! Do you think the formula will last until summer?