Coming upon 18 months

I am nearing my 18 month mark- 18 months since he left, but only 12 months NC.
I keep hearing the magic number 18 as an average healing time. I am not healed. I am still very sad about what happened. I still feel inadequate, lonely, lost. I am starting to get worried that something is VERY wrong with me.
I have been in therapy since he left. I've been to the psychiatrist. I exercise. I (try) to eat right. I meditate. I do things with friends (even if I dont "feel" it). I'm not sure what else I can possibly to do start feeling better. Am I supposed to still be sad and lonely, or is there something deeper going on?
Does anyone know what I mean? Are there others who are/were close to the 18 month mark and get what I feel? Is there anything else I can be doing??
Thanks.