Let's not get too hung up on this. I place myself in the 'grammatical and spelling errors bug me' camp, but only when they appear in places that matter. For example, in supermarkets, where 'childrens clothing' appears on a big sign, or 'fascia's, carpet's and flooring's' appears on the back of a van etc.
And don't get me started on menus (menu's
?) or leaflets...
In my job, decent spelling and grammar mean everything. A comma in the wrong place could have dire consequences. And I find languages fascinating. If you'll permit me to start a sentence with 'and' 
I don't think the OP meant this to be an attack on people with difficulties. Be kind!
Here is one I hadn't though about until my partner pointed it out...
'I like those ones'. No I don't, I like 'those'. Can't pluralise 'one'.
Another pet hate... 'I was sat/stood' instead of 'I was 'sitting/standing'.
There are too many grumbles to list. Shall resist...
'Passed vs past'.
Okay, so that one slipped out.
And for the record, we all have different strengths and weaknesses! Don't give up OP! Stay!