I can understand your questions because I had them myself, and some of the early false impressions I had were demotivating.
I thought I needed 2k kanji and 10k words and N2 grammar to enjoy Japanese content.
Actually that was not true at all.
A lot of content can be enjoyed with no kanji knowledge, <2k words, and <N4 grammar. And then you just learn more as you go and eventually become able to read harder books and manga.
So, for your goals, I agree with others to learn grammar and vocab together. Since you’re already reading, that’s great, keep going! You will get better faster than you think, so it’s OK if it feels slow now, don’t worry, at some point it gets easier and speeds up. For me the most important thing was to be consistent and spend time reading every day.
Rather than thinking “what level do I need to do x” I wish I would have just focused on where I was and taken the next step. Because some steps take much longer or shorter than you think.
So I would suggest looking at three things
- what is easy to read (graded readers? Or ABBC? And keep that up daily
- What is challenging to read? Join clubs at that level and spend a bit of your time focused on this
- what grammar is next and how do you like to learn it? You can use textbooks or bunpro or learning it with reading on Satori, etc etc. Just choose what fits you now! I did something different at different levels. No need to plan right now what you’ll do for N3 or N2 grammar - decide at the time
I regret making goals like x words or kanji per year. It never helped me. What does help is something like - add 3 words to srs per day, or, read 5 pages per day. Then those daily actions turn into thousands of words learned.
For reference I learn about 1000 words every 8-10 months just by reading and looking up words. It only took about 1000 characters per day of reading to achieve that in the early days. That’s only about 5 pages of most children’s books. If the book is very hard for you, it’s still possible to get closer to this in a reasonable amount of time by rereading: start by rereading the previous 2 pages, then read 1 new page, reread that page. Also, reading very easy stories is a good way to increase time spent reading.
Both easy and challenging reading are helpful. Easy reading helps you get through more volume and reinforces your memory of more words. Challenging material helps you learn new words and grammar, but the volume is low so it doesn’t help with repetition as much