Ouch, there is definitely leaks in your game somewhere. You can answer your own question by checking your all in EV. If you were getting sucked out on a lot than is probably a run of bad luck. Even that really can't account for your losses as variance shouldn't be that cruel. If you were getting it in at the wrong time than you need to work on your reads.
I agree. I would start by seeing if you are going all-in while ahead, if not, that may be a red flag that you are behind. Along with that, the usual tips for microstakes as far as most people's mistake go: are you respecting
odds,
bluffing too much, going in with the wrong
hands, and not being able to let go?
There's a difference between NL2 and NL5 other than monetary. NL2 is about learning, at NL5 it starts to be more about winning than learning (and from then on the difference becomes bigger and bigger). So you should leave NL2 confident you have no leaks that better opponents can explore. NL2, therefore, is the perfect place to practice theory and reads (trying to guess what your opponents have). NL2 is not the place to go away from theory (ie. trying to trick opponents,
bluff check/raising, bluffing, slowplay, etc) because too many people will play back, mostly bad plays they would still do if you were playing straightforwardly (calling with medium pair against a 3rd barrel on the river, donk betting, etc).
Before moving on to NL5 I'd see if I could perform good reads. Can I guess what a predictable opponent (which means he's not a complete fish and actually has a pattern you can pick up on. Fishes are unpredictable, in a bad way, and you simply play ABC poker against them without worrying about ranges or stuff like that) has? Is my range correct most of the times?
I wouldn't just move to NL5 simply because my
bankroll allows it. I want to have confidence in my game.
Another mistake people make is that after they get good at NL2, and start having a good run, they will stop thinking about their game. They stop reviewing sessions, catching mistakes, trying to correct stuff. They will get overconfident over a upswing, which is the same (or worse since you probably don't recognize it) as getting on tilt over a downswing.
I hope you still have hand records on those sessions that led to your downfall, so you can start analyzing them. I would bet on overconfidence messing up your game somewhere.
As far as your original question go, "Was I just getting lucky", well, if you are saying that you won $70 or so in an upswing based on luck alone, then logically I assume that a $70 loss would be luck alone as well, right? If we look at it like that, you are neither a winning nor a losing player, the game just balanced out.
I wouldn't like to look at it like that, though. It leaves no room from improvement, and it doesn't feel as logic as it should to me. I think what happened is that there was a leak. For some reason it was kinda controlled when you started. Either because you were respecting your opponents or staying away from risky plays (then you got overconfident and stopped doing this, which leads to my previous point) or you had a leak but it didn't get exploited when you started, then you started catching somewhat better opponents who could explore that leak. So, in a way, you got lucky because your opponents didn't know how to exploit that leak.
I would recommend analyzing your game, as usual. NL2-NL5 (I'd assume NL10 too) are somewhat learning limits, you aren't going to make a living off these, you just want to learn, so that's what you'll do. Study theory, review games, post hands in the forum if you are having doubts, get those leaks checked out.
In the unlikely event you find no leaks, then you can assume you just got unlucky, and eventually you'll grow up again. Also, make sure overconfidence isn't to blame either
Good luck!!