一般以-ward结尾的词，通常表示方向性，为副词或形容词。当用作副词是，美国用-ward, 英国多用-wards, 但也有些英国人受美国英语影响，使用-ward. 当用作形容词时，英美都用-ward,不用-wards。这些词中，afterwards（英）/afterward (美）只能用作副词，不用作形容词，这是个例外。

        目前，因受美语影响，-word形式更多见。于你说的from ... forward 的形式不加s，我没有听说过，只能说美式用法多见而已。我仅以from here forwards为例，即可在谷歌语料库搜索到不少例句，现仅摘选三个例句供参考：

1. But this sacred reflection will be heard and felt for generations on all continents, and especially on the path you walk from here forwards.

2. What we present from here forwards is a mix of selected results from this study with the critical reflections of the authors.

3. And finally, you are going to have to expect the unexpected from here forwards.