Advice/Looking for Info on Micro/Jewerly End Mills

Hi all, first-time poster.

I've been learning by myself with my Universities Bantam Tools CNC Machine, mostly milling PCBs in FR-1 (Copper and Fiber Glass). I've been wanting to use smaller ICs on my PCBs, so I bought some 0.2 and 0.3mm Flat End Mills from China that I knew weren't going to be great given their price, but wanted to just experiment. These smaller bits broke immediately on the FR-1 I was trying to mill, so before I destroyed all ten wanted to know if anyone had knowledge, documentation, etc on using these types of smaller "jewellry" end-mills.

More than anything I want to know if my speeds and feeds sound right. I've never had to calculate them myself, and can't find any suggested speeds for such small end-mills. For the 0.3mm 8-Flute End-Mill I'm using the following auto generated values:
Feed rate: 144.00 mm/min
Plunge Rate: 12.00mm/min
Spindle Speed: 12000rpm
Stepover: 15.00%

I'm going to fathom a guess I should just spend the extra money for end-mills with fewer flutes (like 2), as it makes for a very lengthy bit that seems too fragile.

Thanks for the help.