What is a meltdown? Do I have them? Is it Sensory overload?

Hi, I'm a 23 year old woman/lady with high-functioning autism. I was hoping someone could help me understand how autism actually affects me, I know it's different for everyone and I'm very able but, I have lots of moments that make me feel like my head is going to explode. I cry a LOT, I rock back and forth/in circles/side to side (only alone when no-one can see me, I pull out my hair/eyebrow hairs, I bite the skin off of my fingers, I feel like someone is squeezing my head harder and harder like it's going to explode, sometimes this happens all at once when I'm by myself, is that a meltdown? That's just a few of things I do when I feel very stressed out or upset. I never used to rock (unless I learnt to stop it at a very young age or unless it was when I just went back and forth once or twice then stopped) until about 3 years ago when I met another autistic that did it, I copied her and it felt good so, I did it myself when I was alone.

Almost everyday I feel like I can't cope, especially today because so many things went wrong and I was panicky from waking up from all the noises at my grandparents house (they're very noisy and you can hear every little thing in their bungalow. they don't mean to be noisy), to worrying about things on the bus on the way back to where I live (shared supported living, I hate it and am hopefully moving into independent living in a month) and not being able to stand the chattering so I put some earphones on and listened to music, to breaking my phone accidentally with all my photos and notes on, to missing my 3rd bus by 20 seconds and having to wait 30 minutes for the next one, to being very very late for my support, to going back out to buy a home phone and a ready meal (don't usually eat these) for dinner, to worrying about my messy room that never stays clean for longer than 3 days to feeling overwhelmed and emotionally exhausted, worrying about everything as usual. I just had a really bad day and I think I had a silent, hidden meltdown (or on the verge) on the 1st bus and again, when I got back to my flat. 

I feel like I've become much more sensitive to sound (multiple sounds at once, heavy footsteps, people talking/TV etc.) and it makes me want to cover my ears, smell (strong smells from food or air fresheners/diffusers, certain perfumes etc.) and texture (I've always been fussy with food) and I hate being asked multiple questions by anyone in my family, especially my mum because she has a learning disability (but bought me up mostly on her own) and asks me thousands of never-ending, repeated questions and for help. 

I can usually understand facial expressions and love hugs, I don't ever remember having a problem with them. I get very attached to people far to easily though and I'm highly emotionally over-sensitive.

I just wanted to know more about how it is affecting me, if all these things I just deal with are stimming and meltdowns but, I've just learnt to hide and deal (but, not cope) with them (family trying to protect me) because I know that autistic women are better at hiding and understanding things than autistic men. Is that offensive? If so, sorry, tell me and I'll delete that bit.

Could someone please explain to me how autism affects women. Behaviours they may display and things they don't understand etc. It's like, I tell people I don't understand jokes and sarcasm but, they say I do but, it's just because I've learnt most of them. I never really understood how my autism affected me and I think only now, I'm just starting to realise. I was just looking for a long list of examples from different people with autism or people who know someone with autism. It was explained to me when I was growing up but, I don't remember any of it and I didn't ever understand it and I don't think I was interested the slightest. I've googled tons over the years but, it's google...

My diagnosis' are Autism Spectrum Disorder, Generalised Anxiety Disorder, Depression, Eczema the doctors said I've probably got PCOS and I have IBS, too. Maybe I shouldn't give that much information out? Nevermind. 

Thank you, and I usually type a LOT because things come flowing out so, sorry about the long piece of writing.