Oh you poor thing, I have been there, done that, and sympathise completely. Big hugs.
I'm now 3 years down the line from you and it has got easier but DC1 does still get jealous. As do did I when I was the DC1 with the exact same age gap.
But...they play so nicely together now. Not all of the time, but there are lovely moments.
What made it easier for me in those early weeks, which was tough as a staunch breast feeder, was to introduce bottles once a day, expressed and formula, so that I could handover DC2 to a willing DH or grandparent every few weeks and spend some time with DC1. Usually it was as simple as bath/bed time, but we did have a day out together at around the 3-month point which we both loved, although it was tough to be away from DC2 for that long.
Obviously ignore this last part if you are a committed breast feeder. I still bf DC2 to 15mo, but found this flexibility a real help when dealing with DC1.
I've now engineered childcare and our routine such that both DCs get some 1:1 time with me during the normal week and it really helps us all to get along. After two weeks all together over the holidays, we are all struggling a little!
It's tough. Your OH, if you have one, will naturally gravitate to DC1 and you probably need to help redress the balance a little for everyone's benefit.
FWIW with the DD-then-DS dynamic, the DS's do often, I'm told, become Daddy's boys once a bit older, so you have plenty of DD time to look forward to once that happens.
But do enjoy those DS cuddles in the meantime, until they get too grown-up!