I think most of us have selective memories. We remember what is truly important or relevant to us.
On my first trip to Europe (4 months in 1977-78), I took no camera, so I had no pictures. I had only the most basic of itineraries and plans: start with the UK in September and head south as it got colder, stay in hostels and cheap pensions, keep going until the money starts running out, then head for home. But somehow I remember what I think were the most important parts of that trip. Some were part of my minimal planning and some were happy surprises. I don't go to the same places over and over, but parts of my trips do include things I saw so long ago.
I think by taking lots of pictures you are already using a great method of organization. My assumption would be that the photos are in chronological order. By using some of the suggestions and examples already given, you could supplement that. I do lots of the things others have mentioned to help with the Facebook postings I do upon my return.
I don't keep a journal, but I am big on pre-trip planning. I create a spreadsheet with a row for each day of the trip. The one I have in the works now for my next trip includes the following columns: Day (trip day number), Date, Location, Details (including those for lodging, planned entertainment/tours, transportation), Paid (yes, no, how), Lodging (2 columns, one in GBP and one with an exchange formula to USD ), Entertainment (2 columns like for lodging), Transportation (2 columns like for lodging) Total (2 columns like for lodging).
You can tell by those column headings that this is a planning spreadsheet to give me an idea ahead of time what the trip will likely cost. I add the food and miscellaneous costs later. The Details part is where I put notes about where I want to go each day I'm in a particular place. I'm pretty loose about that and don't necessarily stick to it unless I only have one day to do something big.
I'll add columns to write in food and miscellaneous costs in GBP and deal with the exchange part when I get back home and add up the actual costs of the trip. I'll print the thing out, one-sided only so there's blank space for more notes on the back. With a spreadsheet, I can put in my own page breaks and hide columns and/or rows to print it however I want. I can highlight the rows in different colors to separate the locations, making them easier to see.
The point is that before I go, I have a pretty accurate itinerary of when, where, what, how and how much. From the other responses, it sounds like I'm not the only one who plans their own trips and is somewhat obsessive about these kinds of details. Confession: I also have a packing spreadsheet and one with pictures of the clothes. Truly obsessive.
One thing I did in planning my next trip that I've never done before is to use sticky notes on a calendar and move them around as I did research for the trip. I copied the relevant calendar pages, got the smallest sticky notes, cut them in half and put the location on them. That was the easiest way I have ever done the base planning for any trip and it made it much simpler for me to adjust the nights in each place to suit what I wanted to see/do there. I used 4 colors of sticky notes and alternated them each time I changed locations. I'm a big picture person and I find I'm using that daily in my planning. It's much easier to see the trip at a glance that way.
Happy New Year and a toast to great travels in 2016!