Whenever I spar I'm always out of range when I throw the straight left (I'm southpaw) and I miss the target by miles. I also feel like I'm gonna get countered everytime I throw it, and I almost always do end up getting countered. Even when I try to throw it fast and not over commit I still get countered. As a result, I'm always fighting pretty much with the right hand only and the only time I use the left is on the inside. Any advice?
You get countered because you throw the punch from too far away. Throwing it fast does not change that. Work on this on the heavy bag. Jab-straight left. Step in with the jab- really get it out there- left hand right behind it.
You need to set up your punch better, try setting up with a jab or a feint. Make sure you control the centre line as well, make sure your lead foot is outside his.
Distance is not an easy thing to control. Most likely you're stepping in slow or too obvious in your attempt which makes it easy for them to react. Don't be afraid to be tagged and get your feet moving where they need to be. Also, you might be trying to fight a style that may not suit your abilities.
Cheers lads, will take the advice on board. Guess I'll dust off the heavy bag and start using it again.
Sounds like you lack the confidence to throw your right hand too, just throw it and see how it goes, you should use sparring to try new ideas out.
You can learn to judge distance; just by hitting the bags you should be learning to judge distance. The advice to just jump in there and throw it is almost nonsensical. If you are paying attention- on the bags, hitting the mitts, shadow-boxing- everything you should be doing should be teaching to tell distance. If you are ignoring that and just swinging and coming up short, then you need to settle down. Don't panic and think. if you are not being taught how to position yourself to throw and land punches, you aren't being advised properly.
Also, how much time do you have in sparring? I find that translation of concepts from bag and mitts to sparring takes time because of the other factors that occur when sparring. Hope that makes sense. If you have been sparring a while and this is not a factor then greynotsoold gave some good advice I think.