New Here - Question about Type of Pump and Output

Hi I am new here and so glad to find this board and everyone's very helpful input.

I've been EPing for about 3/4 weeks. I have been pumping heavily since the beginning and was using a nipple shield a lot during the day but my son has gotten less and less efficient with the nipple shield and needing more and more supplemented (pumped) milk.  So here we are.

I use the Medela Freestyle.  I like the pump for the most part and I am pumping every 4-5 hours for about 20 mins and I get about 32-36 oz a day, which I guess is pretty average.  My son, however, has a ridiculously huge appetite. I keep telling myself that I must be overfeeding or that he is going through a growth spurt but he eats at least 30 oz a day, sometimes more.  This means I don't have much of a stock which worries me a little bit.  I would love to be one of these women with a 2 month supply in the freezer but I know I am lucky to at least produce enough for my hungry LO.

My main question is this, since we are doing OK with the Freestyle, should I still look into renting a hospital-grade pump?  I am a little worried about that Freestyle breaking since it was very pricey ($400) and I know it is supposed to be used only part-time and I am now using it 100% of the time.  Do any women here have this pump or do most women rent the hospital-grade pump?  Also, where is the best place to rent a hospital-grade pump? I'm guessing I just need to call up the local hospitals.

Thanks