I know this is a little bit of an old thread now, are you still having issues?
It doesn't look like a good fit. I have in issue with fit because of the folded part of the insert if I put it at the front but not if I put it at the back. This problem [for me] is worse with Velcro than snaps and is also worse on nappies, like Rumparooz, that don't have some PUL at the top part of the nappy inside. Also are you doing a boy fold on your nappies? For example with my BG 4.0 I have the main insert in and the newborn one folded in half and to the front of the nappy.
I have also had the issue that the nappies will only fit too lose and leak or too tight and make reflux worse but there was no way to get a fit in-between that, it is very frustrating. The only thing that worked was to keep trying at least 1 cloth nappy ever day to test if it would fit. You simply can not use a nappy you know for sure is too loose and you can't keep them in one that is too tight. For some babies there are times when you just can not get the fit right and you need to weight for a little growth spurt. I also find that when one brand of nappies is doing this another brand with a different fit works. For me my itti bitti tuttos almost always fit but for a couple of days every now and again they won't but suddenly my BG 4.0 with snaps that normally don't fit will then.
As for a night nappy I personally would not consider using a OSFM nappy. I really think a fitted two-part nappy is the way to go. So far we have used totsbots stretch with a blueberry wrap on nights but in the next few weeks I really am going to have to shell out for a couple of better night nappies. Some of my BTP I am fine with day naps in but some I will only really use for floor time because they just would not hold well enough if his nap was long.
I have to say that I feel your frustration. With DS1 every single cloth nappy leaked very badly on him and at 4 months we eventually gave up. In retrospect he was tiny and needed really tiny nappies but at the time I felt like having a knife fight with my cloth nappies!

With DS2 we had issues but I worked through them. I know how frustrating it is to feel like you are doing something wrong but honestly for some people they work great right away and for others they simply do not fit well and take a lot of effort to get to work. In my experience of 'getting it wrong' so many times my tips are troubleshoot and then troubleshoot some more. Try adjusting the snaps, try doing something different with the inserts, try all the brands of nappies you have and consider trying something new. However do not try at high stress times! Do not experiment on a night or when out because that will drive you to stop using them much quicker. Put a nappy on when trying something new knowing it might leak but forgive the situation if/when it does and put on his more basic sleep-suits not his best clothes. The key to not giving up with cloth fully when they really won't work is perseverance but not to let it get to you either. If one brand of nappies really is not working put it to the side and try it again in a week or two. Remember they are growing and changing shape so quick that one day something might work and the next it might not. For example DS2 went up a row in his BTP and then a couple of weeks on he is slimming out and has gone back down. Also with growing I have the odd day that my itti bitti tuttos (my most reliable BTP) won't fit well and on those rare days my BG 4.0 with snaps will (my worst fitting nappy). If you can work out which nappies seem to have an opposite fit it really helps with babies who get an awkward fit.
I really do recommend a couple of fitted two-part nappies if you can not get BTP to work though. My newborn nappies were quickly outgrown but it took quite awhile to get my BTP fitting well and working but fitted two-part ones have always being bomb-proof on DS2. I found that when I was sick of the sight of BTP using my reliable fitted nappies felt a lot more encouraging than putting him in a disposable.
Sorry for such a long rambling post but I can really relate.
