Vanilla in baby’s milk

Ok soo I’ve been exclusively pumping and baby boy just turned five months. I’m seeing a decrease in my milk as of now and I’m pretty much at the point where I only pump three times a day. I dipped into my freezer stash the other day and my son would not drink the bagged milk! I thought maybe that’s just a bad bag for some reason soo I try another one with a different date and he would not drink that one either! I freak out and start googling. So apparently the taste is different and all this great stuff. I also read tht if I put a drop of vanilla in it it can make it taste like freshly pumped milk? Anyone do this? Anyone have any solutions for mee! I have ALOT of frozen milk and will be devastated if I can’t use it 😵😞🥲 help