Beth,
First off, congratulations on expecting baby no2.!! i know it might seem overwhelming given the current circumstances but it sure is a blessing!!!!!!!!!!
Now, about Asher i have many thoughts about this, by looking at the info you provide.
I will start with the nap. Since he's already taking a short morning nap, we can work on cutting it till eventually disappears and encourage the evening nap to be a bit earlier in the day and to last for longer. To achieve that, I'd suggest to try nap1 at 830-900 and make it short, more like a catnap that helps Asher to get through his "real" nap without being overtired. You can even try this nap to happen in a different place than his crib/bed so he won't associate short sleep with the place he actually MUST sleep for long periods. So nap 1 can either be at the car (running errands), stroller, the couch or even your bed watching cartoons. Sometimes this kind of naps end up being quiet and relaxing time.
Then, and depending his waking time in the day and how long the catnap was, try nap2 (or the real nap) to be around 1245 or 115. Not later than that cause we don't want Asher waking after 330 pm and hence having a late bedtime. Bedtime should be no later than 730 and on days he wakes extra early, have an early bedtime to compensate for the lost sleep.
Having the schedule business organized, we can tackle the going to sleep. I don't know about Asher's temperament so you might want to check Sarah's post on the Faq's section at the top of this forum to read through the Teaching Independent Sleep thread and choose the method you think will suit you and Asher best. After you pick one, stick to it no matter how hard it seems the first few nights. You have to pick a starting day when you're not particularly tired or stressed out cause tears are to be expected. IT's gonna be hard but totally worth it!!! give the method a go for a week before you make any adjustments to it, to see the whole picture and realize what needs to be changed. If Asher asks to be rocked, try some patting in the back/forehead instead. The goal is to keep him in his crib and to help him learn how to soothe himself in there insted of being picked up.
By doing this, I think you'll be providing plenty of oportunities for him to sleep and to catch up on lost sleep. That should be enough to make morning wakings a little bit later, but we never know. Remember you have to be as consistant with the new ways as you've been with the old accidental ones to really make sleep training work. Be sure to get started when Asher's not ill or feeling poorly. Check with your pediatrician about pain medicines before bed to help him cope with the molar pain, cause it sure is another input on the poor sleep mix, and it's an ugly one.
Keep us posted and updated!!!!! we'll be here for you!