All of the above is GREAT advice. Took a lot of the words out of my mouth. Keep in mind-a 10 week old puppy is a baby!! Don't expect him to not need you! He has just been separated from his mom and littermates and it's going to take time to adjust from the only home he has ever known. He learns to trust you through positive interactions.
Expecting a 10 week old pup to be housetrained is expecting too much most of the time. The potty training thread is spot on-but it's IN AND OUT, IN AND OUT, IN AND OUT. For weeks. Eventually he will get that potty=outside=noms, and potty inside=nothing. (don't punish-he will just run away and do his business!) But the more vigilant you are, the faster this goes. I got Sam at 8 weeks and he was 95% trained, even moving houses, by 11-12 weeks.
It's completely okay to leave him alone when you know he doesn't need to pee or eat. He might fuss, but giving him a toy will help keep him occupied. Rain's explanation is perfect and what I usually say. You need to be able to take a shower and do laundry and go grocery shopping. He needs to also learn how to be left alone without developing SA. If you NEVER leave him as a baby and then all of a sudden start leaving him for chunks of time, this is going to be a problem. Start small and desensitize him as a pup. Take a shower, then go to the store, etc. Increase the time.
I'm a "single puppy mom" most of the time. My BF and I live 1000 miles away so most of the time it's me and Sam. But when I go home, Blake loves helping take care of him, playing with him, etc. Make sure your BF knows how much the pup needs to be taken out, etc. and let him know it's stressing you out so he can help.
Nothing you are saying is abnormal. Do a board search and you will find a ton of posts like yours of people who grew up with dogs, but when they get their first on their own as an adult they either forgot (because the parents did a lot of the work) or greatly underestimated how much effort a puppy is. I'm not sure why you're not crate training, but I would strongly consider it, it's the best potty training and anti-chewing up the house tool there is. Plus it makes for a portable puppy home if you need to travel. Read the crate training sticky, it's very helpful.
Good luck with your new little guy-you'll be fine. The work involved decreases as the weeks go by.