First time handraising kittens, HELP PLEASE!

Hey guys, I’m new here and this is my first time hand raising a kitten. My boyfriend found a nest of two kittens last week near one of his work sites, and they were both crying, cold and hungry. He left his sweater with them but when he came back the next day only one was left and it was more upset than ever. He was at the work site all day with no sign of the mother or the other kitten anywhere near. After a few days he brought the remaining one home.

So now we have an approx. 2 1/2 week old kitten, which we are trying to do right by and I could really use some advice! We’ve got him on formula, and we’ve built him a cozy nest. I’ve been burping him, and helping him pee, but it’s been 2 days since he brought him home, and he hasn’t gone poop. I’ve read on here that 2-3 days is normal, but I’m still concerned. So I spoke with my other cats vet on the phone today to ask about using vegetable oil and he didn’t recommend it as he said it may make baby sick. He did however recommend canned pumpkin… but I’ve used that before with my mums cat to stop diarrhea. Thoughts and experiences with this? Also I would like to know if it’s normal for him to wiggle around and cry when I try to perform the triangle method? He’s so active when he’s awake like he has somewhere to be!

In addition, I’m not 100% sure on his age. I said 2 1/2 weeks as a guesstimate, based on the fact that while he has no teeth as of yet, his eyes are open, he is holding his head up and crawling/walking around nonstop while awake(albeit very wobbly), and he is eating around 10ml of formula a day! So any information to help me with determining his age would be appreciated. I can also provide pictures if needed.

Like I said before, I am inexperienced with hand raising orphaned kittens, and such young ones as well. The youngest cat I’ve cared for was 2 months when I got him, and he’s going on 5 this year. So I need help in making sure that our newest little guy makes it. The fact that the mother left him makes me worry that she had her reasons, but despite that I wanna do all we can for him. But so far everything I’ve read talks about entire litters to at least 2 or 3 kittens, not just one. Will he be alright if he’s alone? Silly question maybe, but like I keep saying, I’m really new at this!

I would like to add to all of this that we will be taking him to my vet next week as we can’t get in this weekend. But in the meantime any tips, tricks, advice, or just plain ol’ encouragement would be amazing! Especially since everyone on here seems to have much more experience with these babies than my vet, even though he is a wonderful vet to my other 3 cats! Thanks!