Poker How long should it take to beat 2NL?

I'm struggling on 2NL right now.

After a huge downswing, and some serious losses from the first 15k hands, I deposited more cash after tilt made me lose all of my bankroll.

I'm playing much better now after correcting many of my rookie mistakes (it is just my first month of playing). I'm winning buy-ins, but I'm losing them as well.

To make a long story short, it feels like I'm sometimes taking 2 steps forward, 2-3 steps back.

My losing days are so rough it's getting to me, and they're happening more often than my winning days.

I added $40. I got up to $48, and then went down to $28 over the next few days. I started recovering, went back to $41 over the next week, now I'm down to $26.

I'm not playing more than 600-700 hands per day.

For some of my stats in 20k hands, VPIP: 22.3, PFR: 16.16.

Essentially, how long should it take to beat 2NL?

Are swings like this common at all stakes?

I'm still a losing player. But I believe I have everything it takes to become a winning player.

Thanks!

Source.