How can I be sure I am lonely?

I would say if you look at other people beeing together and you think " They are stupid" or "I wish I could have this". Or if you have a general feeling of not beeing able to talk with anybody or not relying on anyone. Sometimes, times are necessary when we are alone. However, feeling lonely is different. Just remember that everybody feels lonely at some point of their live, so basically were all together in this feeling.

if you start yearning for anyone elses company and literally anyone will do but not be able to do anything about it

Feeling lonely is a natural thing.. it happens to majority of us. One way to knowing, is a feel of helplessness. The feel of abandonment, no one is there. There comes a need of a want, whether its social interactions or just simply being around others. You can think to yourself if either those situations would help in the case of your loneliness. Some individuals are surrounded all the time and feel lonely. It is just a simple thing that makes every being unique, looking for the "right company" or someone to get along with.

You're lonely if you feel lonely. Simple as that. No sense overthinking it. Maybe you're surrounded by people but still feel lonely. Then you're lonely. Maybe you spend a lot of time alone, but you don't feel lonely. Then you're not lonely.

The best way to be sure you’re lonely is to write down all the times you feel this way in a day then at then end of day look at what you logged.

If you look around and see others having fun and wishing that was you that’s a sign of feeling lonely

Loneliness is completely separate from being alone; enjoying one's company and the solitude. If you're feeling that you're missing social interaction or even human contact, then you are probably lonely. Think to yourself: (anxieties and worries put aside) do you want your situation to change? Do you feel that you're missing out

Well, the definition of being lonely is being without friends or company. But being lonely obviously means something different for everyone - just because you do not fit this definition does not mean you aren't lonely.

The meaning of loneliness can vary to each person. Generally, loneliness means that feeling sad/depressed because of not having any company. You can try to figure what a real company personally means to you.

You have a feeling of obligation to make connections, but look desperate doing so. Feeling long periods in which you don't feel like you have any support, or anybody that can help you through.