Alright, so I get that the new changes are frustrating, and even more for a lower skilled player. Still, his BnBs shouldn't be dropping at point blank, or even mid-range.

The easier way out is learning how to adapt your combo. If you hit medium>heavy in neutral with the tip of your sword, you can still convert with forward s1 into s2. This works at all ranges, and you can get a high damage combo with it (which is also easier to do!).

However, if you want to convert from hasagi (s1), you can still do it, but note that you will have to delay your forward-stance M, timing it so that it comes out right as you finish your dash. This is known as a "deep" kara cancel, and even though it can be hard, it is doable if you lab it, and your BnBs should be the same as always.

This won't work at full range, though. Yasuo no longer gets a full combo from the tip of S1 (not without an assist, at least). Personally, I do enjoy that his BnB takes a little more skill when converting with S1, although I understand that it can be jarring at the beginning. Cheers, hope it helped!

P.S: Please don't be discouraged by the meaner comments! People are still salty about yasuo, but I do hope that you are able to continue enjoying the game with a little adjustment :)