So I believe that the “5%” you read as your gravity before bottling was around 1.037 hydrometer reading. I found this by looking at a hydrometer label that had a percentage scale on it as well. If this is indeed the case you should not have bottled. They could blow up. I would take a bottle and open it carefully under a towel, outside, and then poor that back into your hydrometer jar and take a reading from the scale that that reads something like “1.035, 1.040, 1.045”. If you are below 1.020 then you should be fine. If you are higher, then you could have enough fermentables left to get some nice pressure in the bottles assuming you have enough yeast or oxygen left to keep fermenting.
What kind of yeast did you pitch and how much the first time? If you pitched a single vial or packet of lager yeast it may have NOT taken off like a rocket within the first three days because lager yeast typically takes longer to get going than an ale yeast. I have pitched quart starters and had them take a couple days to get rolling. Did you aerate the wort?
What kind and how much yeast did you put in the second time? If it got going right away, and you only pitched one vial or packet, I am guessing it was an ale yeast. Six days of fermenting is enough to finish if it isn’t a big beer and the yeast is good. However, at 55 degrees, and if not an ale strain that can still do well at that temp (like Nottingham, Pac Man) then you likely did not get full fermentation.
Lots of unknowns but you still have brew underneath your belt. The good thing from this whole ordeal is the lessons learned. The first brew is typically a crazy one for any first time brewer. Just making something that looks and taste kind of like beer is great for the first time or two of brewing. Yet, a trained monkey or a pig with thumbs can be taught to make beer. It is making good beer and being able to brew consistently that is the trick. This will come from learning your processes and a high level of attention to detail. Temperatures, times, gravities , and specifics are key in brewing. Plus, if you are seeking assistance from others here, the more (accurate) info you can provide, the better assistance you will get. I hope this helps. Good luck. Be sure and get everyone in helmets and safety goggles!