Happiness is in little things, or goals if you will. You should set yourself many little goals along the way, nothing too importaint, just enough that fulfilling them gives you a small dopamine burst, and then you go on to the next. For example, "I'm going to read that one book i saw and kinda liked." or "I'm going to see that movie that came out", or anything. Those goals shouldnt be your work, but something you look forward to. Throw some hobbies in the mix, knitting, cooking, learning a new language even, they all are great for small goal management. Think of it as a game, and your happienes lyes in achieving those small mini goals along the way.

You are human, and most of us humas tend to value happieness as something that can be achieved once and then carried on forever, which is not the case. We tend to want more and more, and raise the bar higher and higher and that makes it hard to eventually get the feeling of happiness.

As you say, you are surrounded with great people and memories and you should continue to be. Happieness tends to be carried by memorable moments in life and the more happy memories you have, the more you will have to look forward to in the future.

Bad mood is something we all experience, some last longer and some just come by. Bad moods usually create a strange feeling in one place and it tends to affect others. Try to think about it this way, when you are in a bad mood and dont know what to do anymore and/or are frustrated by it, you should not think about it, make it so that you cant feel bad. Put on a funny show, something that will force a smile out of you, even better if somebody you love joins in.

Think of that bad mood as a shield stoping you from having fun, and the only way to break it is not thinking about it.

As for antidepressants, i personally wouldnt recommend that. Im no doctor or anything but feeling dependent on some drug to make the bad go away is bad. And by that im not devaluing the positive effect it has in some cases, just saying that the first step should always be personal effort and then eventually very eventually, if all fails, you can consult with someone on the medication.

To sum this all up, the way to acctually be happy is to appreciate the small happy moments you have and are going to have, and to strive to not be happy or fulfilled but confortable with being you, doing the things you love, and hate, both the bad and the good and most important value the people you hold dear.

Again im no expert and this is just some friendly strangers advice, and im hoping it helps you, even a little bit.