Well for tapas you only have one episode. Generally people may not subscribe cus you might drop it. and it miraculous that you even gained any subs, which is an accomplishment
Let me be honest with you, webcomic growth is slow...very very slow.
You just started.
VERY RARLY any comic gets double digit subs in the 1st month. And usually its because they already have a following, they advertise alot already before hand or they won the lottary.
This is comming from some one who had a comic for a that only gained 12 subs (it wasn't very good) and now has spent a year working on a comic that has 65 subs here, 16 on webtoons(idk how), and 6 on comic fury. And have been updating every week for a year now.
I don't work in the most popular genre nor have much a social media presence. So really it was up hill battele.
Really the best I can say is just lower your expectations. Treat it like youtube, majority of youtubers rarely break out even 100 subs and webcomic audience is alot smaller