Theoretically, each week is a new PB for me as I've never done those weights before for reps / sets...When I started in July, I just used to try and beat my PB each session, and not do any 'sets' so to speak.
For instance, this is me in July
This is me now
As you can see, strength is completely different.
Maybe I should just jump to 90KG on DL's and try and do 3x8, but I know my strength won't be up to it as much as it should be if I slowly worked up to it.
I've never actually done any 'strength' training so to speak, it's only since Christmas I've actually had a set routine, so far I've not hit a plataue... If I had a Bench Press video I'd show you how close I am to failing, I'm practically at my max there, wheras on DL's I'm not...
I dunno, poundages are going up each week, so far this is working for me...I have an odd body, somehow I always injure myself one way or another if I just jump in to things (for instance my lower back in buggered right now...Just from supersetting squats with shoulders =/)...So maybe I've just become over cautious?Who knows
Either way, I've put on some mass since I started, and I've always found it hard to do that. Currently 94KG~, give or take a poo
I think this was covered already, but I haven't read every reply. I'll just add a +1 that you might be taking this a little too slowly. I did something similar, squatting 3 times a week. I added 2.5kg per session for a while, to over 130kg x 5 x 3. I'd stall a couple of times here and there, de-load a for a week, then blast past the sticking point. After 130-135kg, I would do a light Wednesday, so that I was only going up by 2.5kg on Mon and Fri. That was fine until around 140, then dropped it to 2.5kg a week. Those last couple of weeks doing that sort of progression is like torture. Every session ended with, "there's no ****ing way I'm going to be able to add another 2.5kg next session, no way!" But you just do.
After you've stalled and de-loaded a couple of times, it's time to move on to a more advanced routine where the progress is a little slower, and you need to think more carefully about your programming. Where you are strength wise at this stage, is different for everyone. But most average guys should make a damn good go at getting over 140kg doing this type of linear progression. This was one of my problems with SL and 5x5, the progress didn't seem to be as good for most people.
I'm all for improving technique, to a point. I guess I've just been lucky to not have too many issues with training. Sure, I've had minor stuff that requires a little down time, but these things happen in training, even to 'experts'. It doesn't always mean you need to restart your training from scratch and you've lost all your gains. A lot of the time there's no damn good reason as to why you're hurting; sometimes they come and go. As you become more experienced, you learn which pains you need to take seriously and what you need to do about them.
Oh and another thing, forget doing 3x8 on deadlift. Do 1 or 2 heavy sets for deadlifts. I liked either doing a single heavy set of 5 (that got me to 180) or a two or three sets of heavy triples (that got me to 200). You don't need much volume on deads in the beginning. Just do that once a week, and really push yourself.
I dunno, I'm rambling now.
My main point is, you're leaving a lot behind and not bringing it to the bar. If you do this 'right', you should getting slightly scared just before approaching the bar. I used to sometimes have trouble sleeping the night before a big session. 
Happy to stick with SL if it makes sense to.
