So, my mom drives me crazy telling me that I can only put LO on flat surfaces till he is 3-4 months. Reclining is so to say bad for their weak spines. Any half sitting is bad in her opinion. And all the stuff I have (stroller, car seat, bouncer, swing, etc) is reclined. I reached the point where I started to freak out if it's true or just outdated info. Have you heard anything about it?