I have several mint types growing on my window sill indoors. I have noticed that some problems with them:

- Leggy stems. I have found on internet that this caused by insufficient light.
- Curly leaves - one side of leaf becomes a bit twisted downwards and towards central stem. Reason unknown
- Small discoloring towards yellow color on leaves. Reason unknown.

What may be the source to 2 and 3 problem? What do you recommend to solve them? I do water them regularly, tried to add some universal liquid fertilizer.

Also here are some pictures of mint that I have. Please help me identify types of mint on them. In my opinion they are:
- picture 1 - Mojito mint
- picture 2 - Peppermint
- picture 3 - Apple mint

Your plants look healthy to me.
The Mojito mint looks like mine--it is back from light too.
It would probably be less lanky if it was in more light.