Initially, I use to think merit is by chance ( i.e something that will just happen) or lengthy article ( i.e writing too many paragraphs and the rest of them), but I have come to realize that, it is more than that.
I have being discouraged several times because of my numerous posts and replies yet no merit then. Even now, some times I use to be discourage. However, the only way to get merit is by posting quality article ( that is what determines merit) which almost everybody is aware of now.
In summary, don't look at the quantity of post you have make so far but instead try to adjust, I mean improve in your posts, above all be consistent and patient that is the key.
You catch the right point. There are many accounts whose post quantity is above 2000 but they don't get a single merit especially such users are bounty hunters. Moreover there are many accounts which have not received merit even in last 2/1 year. To get merit, a user must pay attention to the quality of his post, not in his post quantity or length. I would like to give you another suggestion at this place that first remove the merit earning from your mind and spend time in the forum and ask questions on the topics which you find difficult to understand.
And besides another thing is to present what you know or what you are learning, basically help the users of the forum and find out new ideas, you can see your merit will come on your own.
I would also like to suggest you to read this topic-
https://bitcointalk.org/index.php?topic=3182178.0