Hi there. Well, I'm not sure. Between the ablation and the tubal, your doctors were not expecting you to want another child. This is one of the reasons they often have minimum ages for performing a tubal. That is considered permanent in terms of making a woman infertile. That coupled with the ablation and no periods (which means no ovulation), this would be complex. They CAN reverse tubals though. I'm not sure of the success rate though. You'll need to see a specialist most likely. I wish you the best. good luck
Your problem is more the ablation than the tubal, and the tubal is problem enough since reversal is expensive (not covered by health insurance), painful and often has worse odds than doing IVF. But if you are not having periods, this means your endometrium has been destroyed entirely, not that things are somehow just dormant, and without endometrium your uterus is not going to support a pregnancy. There are stories of the placenta burrowing into the uterine sidewall and causing a risk to the woman's life, and pregnancies after ablation are considered to be doing well if they reach 30 weeks. In other words, you would risk not only the baby's health or life, but your life. For the sake of your other child, you don't want to risk your life.
The good news is, I would not think that your ovulation has stopped (presumably you didn't have your ovaries removed). Even if you are not having a period, it just means your endometrium is gone. This means you could possibly (with a good doctor) get some eggs withdrawn, have them put with your husband's sperm, and get embryos. Then use a gestational carrier ("surrogate mother") to carry the baby. This seems eminently possible to me. (Expensive, but once you had the tubal and the ablation, you walked yourself into the realm where the only options are expensive.)
Have your ob-gyn refer you to an RE (a reproductive endocrinologist or "fertility specialist") and see what you find out. It is do-able, you just have to decide that when God closed a door He opened a window, and be glad you have the chance for a child no matter who carries it.