Lost a batch of newly uploaded photos on Photos when it asked me to switch to iphoto when I was adding old photos, how do I find the photos?

I recently upgraded to the new OSX Yosemite. Before I did not have any photo storage program on my Macbook Air. After getting the new Photo with Yosemite, I decided to start uploading photos from my Iphone. I uploaded a few hundred photos which I could see on Photo.

I also wanted to put some photos from my old Macbook pro onto my Macbook air, and had them on my desktop (I had transferred them with an external hard drive). They were lumped together under "Iphoto library". When I tried to drag this icon into Photos, it asked me if I would like to switch from Photo to iphoto, I hastily said yes, and all of my old photos were uploaded. Now, I have all of these old photos on Photo, but I can't find the photos from my Iphone that I had originally uploaded, anywhere on Photos, or in the computer. I can't find anything that asks me to switch back to "Photo" from Iphoto (and don't know if that's a thing).

I really hope I didn't accidentally delete the photos when it asked me about switching to Iphoto, it seems like the photos should be somewhere on my computer.

I already had deleted them from my iphone and haven't gotten the Cloud up and running yet.

Does anyone have any ideas or suggestions about this? How can I find the photos that I first uploaded to Photo before this confusing "switch" happened?

Thanks so much! Any thoughts are appreciated.