I know exactly what you mean by “stretchy.” As one Beginner to another, I think it’s time to change your strings.
First, good maintenance goes a long way. Wipe your strings off with a clean soft rag after each time you play to remove oils & acids left by your fingers. This will extend the life of the strings and help prevent corrosion.
When the time to change comes, you may not see any apparent rust or corrosion, but that “stretchy” feeling is a dead give-away. I call them “rubbery strings.” You can bend them, pull them, pick & pluck them…and you think you are playing like a wild man, but there’s a little something missing. They do not seem to be as loud as they should be, especially when playing like a wild man. The notes come out, but they don’t jump out with authority. Everything about them seems just a little muted & mushy.
Then when you go to change the strings, you can’t help but think you are wasting a perfectly good set of strings, maybe two, depending on how badly you screw up re-stringing. (I am sooo guilty of that!)
But once the new strings are on & you are all tuned up, you will know right away you did the right thing. Stretchy, rubbery strings, Bad. New strings, Good!
Finally, watch a lot of different videos on “How to change banjo strings.” Everybody seems to do it slightly differently, but they all have some important things in common, like winding them in the right direction. (“Another point of error for me,” he said in embarrassment.)