I completely relate to your post OP and had the exact same issues in the past.
The key is to first of all accept and respect yourself. Love yourself. I am sure you are a genuinely lovely person but are convincing yourself otherwise and have been for a long time. I was the exact same.
Think about it - if you yourself insist that you are boring, its hardly likely anyone else would find you exciting.
But you are not boring - you are putting yourself down. Stop it! You deserve better!
Dont listen to your own unwitting negativity - rather, try to take an objective reality based view. For example, you say you are boring and a wallflower. Yet, in your first post - you mention two friends and two social events. So, clearly, you are a likeable person whom people desire to befriend and spend time with. Your bad impression of yourself is demonstrably wrong.
That is the reality. Accept the reality. Do not let negative thought patterns convince you otherwise. Accept the reality. Its important to be aware of and recognise bad thoughts which paint a negative picture, which isnt based in reality. When you recognise them - say NO! Discard them and replace with positive thoughts. It can be hard to do, but do it you must.
Dont put pressure on yourself, in social situations. In any environment, feeling under pressure can make our minds go blank and we struggle. Try to relax.
Making small talk is actually quite easy, if you relax, give yourself space to do it - whats your name, where you from, what do you do for a living, what about that xyz on the news, have you seen that new film, tried that new restaurant, blah blah
These little throwaway topics help us ease into peoples company and to relax, leading to friendships or deeper topics etc.
Dont obsess about feeling shy or being anxious. There is nothing wrong being shy. Often obsessing about it is actually the cause of it in the first place. Just be you. You are wonderful.
Dont compare yourself with others. Its important to note that YOU even with the shyness, anxiety etc, are every bit as valid a person as anyone else, including those who seem so popular, funny, social etc. Your experience of life is every bit as valid as anyone else's and is in no way inferior. Our lives and personalities are all different, but they all have equal worth. Learn to accept yours and do not feel inferior to, or even envious of, others. You are as good as anyone. Accept yourself - no one is perfect and we all have flaws - but accept yourself and your flaws.
Dont worry what others think of you. You do not need anyone's approval or validation. If someone doesnt appear keen or interested in you - so what? You dont need to spent time with them, or see them again. They obviously have poor taste. Approve of yourself - and that's enough. I spent so many years in extreme contortions about what others might have thought about me, or something I had done. For a long time now, I have not given a f*ck about what random people think. I highly recommend the latter approach, its hugely refreshing.
Fight to feel happy and at ease with yourself. It took me a long time to realise that happiness and confidence is not simply a product of our circumstances, but rather a choice. yes, a choice - to see the good in ourselves and to feel happy, even if our lives are not perfect. If you feel down, say no! - balls to feeling low, im going to be happy - even if I feel anxious, or if work is getting me down, or if I feel overwhelmed or had a bad day. Im going to be happy and I deserve to be happy.
Its genuinely about making a deliberate and positive choice of outlook for personalities such as ours. Its not always an easy choice, thats why I say you have to fight. Fight and be happy. No one else will do it for you. You deserve it and owe it to yourself. Do it!
If we feel happy and accepting of ourselves, we naturally radiate that out to others - but equally, if we put ourselves down and feel low - that negativity radiates out also. Naturally, those with a more positive glow about them tend to be more appealing to those seeking a chat or a date or whatever.
You have deeply ingrained a false negative impression of yourself into your mind - and no doubt reinforce it regularly with negative thoughts. And so its not a 5 minute fix to climb out of this. But you can do it - you will do it. Sure, you will have ups and downs, but you will do it.
I hope my rambling above might be of some minor help! The first step is to stop that negative reinforcement and to accept and love yourself. Then we are cooking with gas!
I am sorry for such a long post, but this is a topic important to me. I needlessly put myself through the mill for years with stuff like this. It completely ruined my teenage years -a very bleak time - and undermined my 20s. Whatever age you are, dont let it ruin your times - get that monkey off your back and enjoy life like you deserve.
Made a decision to change right now. Try to follow the points above, it gets easier and eventually seems natural. Because it IS natural. What isnt natural is always doing yourself down and making yourself feel worthless.
I learned all this from a decades long mental war of attrition (victorious!) and so believe me its better just to accept advice than go through that.
As a positive step, why not join an evening class - like learn a language, or something you have always wanted to do. it will get you out, meeting new people and help building your confidence. There is a ready made topic to engage with others on (whatever the class is about). It will make you interesting to others and create another small talk topic you can fall back on. Do it!
Life is for living - enjoy!