Hello and Welcome to the Chrons! You've come to the right place for help with writing!
First of all, I take it you are being careful to submit the right stories to the right places? ie you're not sending SFF to a magazine that wants romance or vice versa, or pieces of 10,000 words to somewhere that has an upper limit of 2,000. I know that sounds obvious, but it's sometimes an easy mistake to make as not every publisher/magazine has the clearest of guidelines, unfortunately. Added to that, even if a magazine wants SF, it might not want the
type of SF you write, so read back through previous editions to see what they aim for. But when it comes to it, there are multiple reasons why good work isn't accepted -- your particular style might not fit with them, or they might simply have too many submissions and don't want anything that isn't absolutely perfect.
As Teresa has mentioned, it would help us if we knew how many stories you'd been submitting to garner those 180 rejections -- if that amounts to 180 stories submitted to only one or two sites, then it's a different matter from, say, 15 stories submitted to over a dozen sites. However, I do wonder if you are confusing quantity with quality -- I've no knowledge of critters.org, but to me "most productive member" simply means "produces a lot" which says nothing about the actual excellence of work produced.
To be honest, if you've only been writing in English since April, then it may well be that the stories themselves aren't yet as good as they could be as you're still learning your craft -- after all, you wouldn't expect someone to say "I began playing golf in April but I've not won any prizes yet." Even if English is your second language and you're an accomplished short story writer in your native tongue, it might not be quite as easy as simply translating word for word as different cultures have different expectations of stories, just as different genres do.
I know you say you've paid beta readers, but are they actually experienced/successful writers/editors in your chosen genre? Do they give feedback which is actually helpful or are they simply telling you what they perhaps think you want to hear?
I've been writing stories since I was a child, which is a great many years ago, and I've been taking it seriously for 14 years now, yet I'm still writing some stories that I think are great but which the two members of my writing group -- both with MAs in writing -- say aren't good enough, so I have to rip the stories up and try again. If the beta readers you've got aren't doing the same for you on occasion then either you are supremely talented and it's a mystery why your stories are rejected, or they're not doing their job.
What I'd suggest is that you stick around here for a while. Once you have 30 counted posts you can put a few hundred words of a story up in our Critiques section where you will get excellent advice and help -- I know you've had feedback at critters, but our advice will be disinterested since there's no requirement on anyone here to critique. Have a look through threads there and you'll see the standard of help we give.
Meanwhile, we have monthly Writing Challenges which you can enter -- you're well in time for December's Challenge which is here
DECEMBER 2020 75 Word Writing Challenge -- READ FIRST POST!! Although this is flash fiction of only 75 words, the basics of writing short stories is exactly the same -- a good idea, well expressed, with well chosen words -- and there will be a 300 Word Challenge coming in January which gives more scope for storytelling. You'll get speedy feedback on your work there by way of mentions and/or votes, and when voting is finished you can ask for specific advice if you think the story didn't get the attention it deserved.
So, don't give up just yet. Stay here and let us help you take your work further!