Two weeks I bought a $10 everbearing strawberry plant from Walmart. It looked the most alive out of all the Walmart options. I immediately repotted it into a larger pot that stays out on my balcony. I use a moisture meter and have watered her just about every other day so far.
Last week was very warm with a couple +30C days and she seemed to be quite happy in the sun. She started to bloom a few flowers, I cut off the first couple to encourage her to grow into her pot but now I just let them bloom. I quickly grew attached - but this week has been plagued with problems. She has been surrounded by fungus gnats for the past few days - and this morning I noticed she had a mushroom sprouting! I read that mushrooms aren't bad for plants- but I don't want them. Clearly I'm overwatering - but my moisture meter has been telling me her soil's right in the middle (not superwet but also not dry).
Are these temporary problems? Are Walmart plants just unreliable? I don't want her to spread mushroom spores and fungus gnats to my other plants. What steps should I take?