Sizing I-beams for two Floors to replace LVLs
Notes: 


I am not a licensed architect or engineer.   I do however produce plans that I get a stamp on or have the local inspector agree to.    
I usually would not give someone advice on load beams that are not uniform - you are spanning two different load configurations here and doing a bit of stacking.   
Since you already have LVLs and the description of your issue I am assuming that the load calculations are right, footers are suitable and working, and the support beams are sufficient.


I use https://www.engineeringtoolbox.com/ for a lot of information - I actually found the site from an architect that I use.   The chart below is from their site.   I ALWAYS add an extra 25% of allowance to anything I size myself.  You should be using this as a reference and work with someone that can look at the full layout of your building.