Husbands low sex drive

I’ve been with my husband for almost 12 years, married for 5 years this year. I really do love him, he’s my best friend and an amazing father and husband. He’s always had a lower sex drive than me, usually only having sex 2-3x a month max. But in the last year it’s been non existent - we’ve not had sex once and he hasn’t even attempted too. We’ve grown apart romantically because of this so in Dec we started counselling.. it got better for a month or so but we never got to actually have sex as he would go soft as soon as we tried to start.. fast forward 3 weeks ago he went and had a blood test and found out his testosterone is lower than it should be. Research says testosterone injections lower sperm count - and we want to have a second baby (which is hopeless with the current issue). I don’t know what I’m looking for here - anyone else experienced similar? I’m so lost!