Do anyone know any good site or program where you can make nice easy graphs that are displayed over time? I have looked at a few, but I have not
found one that seem to be focused on what I want.

What I basically want is an X axis that is the date, and you can choose how long you want to see, like last 7 days, or a month a year etc. And then you can add "items" that you can toggle on or off, like for example say you wanted to record your income in one item and how many kcal you eat in another. Then you would just insert those numbers and what date they refer to and you could see their graph show up. Then you could toggle items on or off if you want to show them.

Basically like this graph, where you have one line with the date, and the other with numbers and then you have different colored lines for different items and you can toggle them on or off to show or hide them: https://dl.dropboxusercontent.com/u/4047131/5/2016-05-11_115901.png

I take it something like Excel/OpenOffice doesn't meet your requirements? Does it have to be online? Do the data points have to be regular or can they be all over the place?

Google has a charts API. You could set up your own webpage and use that. I few of my colleagues who write android apps use it when they need a chart they just pop up a web view.

https://developers.google.com/chart/

Nanohah: Can I create a graph like in my picture example where the x axis has the date and I can just add in new numbers on those dates and it will save it? It does not need to be online.

Buster2000: It sounds complicated to deal with an API for this, I need to also make a webpage to use it?

What I am looking for is very basic in my eyes, just some chart where I can create items and then insert numbers for specific dates and it should show them up at those dates, and I can look at it over the week, month or year etc and also toggle individual items on or off to hide and show them in the graph.

You could build something like this really easily using a package like HighCharts and some JavaScript glue.

Nanohah: Can I create a graph like in my picture example where the x axis has the date and I can just add in new numbers on those dates and it will save it? It does not need to be online.

Buster2000: It sounds complicated to deal with an API for this, I need to also make a webpage to use it?

What I am looking for is very basic in my eyes, just some chart where I can create items and then insert numbers for specific dates and it should show them up at those dates, and I can look at it over the week, month or year etc and also toggle individual items on or off to hide and show them in the graph.

You can create a graph like in the image you showed using OpenOffice Calc (free). You can do it so you can add more entries later but that will require either you to know in advanced how many more entries you will have or a little bit of effort each time you add new entries (it's very little effort but it's more than just typing in a few new numbers). I should add that toggling items on and off is not very trivial with OpenOffice though, I can't see how to do it at all short of making a new graph.

You are asking for quite a flexible and user friendly thing where you can just add data on the fly and have it rebuild itself and I am sure there is something like that out there. This does the job: https://nces.ed.gov/nceskids/createagraph/default.aspx? It mentions saving so you could maintain something on there if it's just a personal thing and modifying seems simple enough. It doesn't seem to let you hide series though.

A few years ago I made an app and needed quite a dynamic graph, I think I used this: http://www.android-graphview.org. It is Android so that limits it depending on your needs but I remember it being quite easy to use. The graphs look good and since it's programmable you can have it do pretty much anything you want.

It's unclear from your post if you just want one specific graph that you can do yourself or if you want a more general solution that you intend to use somewhere or even if you want the graph to be in some other project. For your own personal graph, for your own interest I would just use something basic like Office/Open Office or the equivalent depending on your OS/device.