I did that before- counting calories and tracking points at the same time but only because I was curious to how many calories I was taking in. Right now, I'm just tracking points since it's a lot of work to do both, lol.
I don't know if 1800 calories per day will give you the same results that you were expecting from WW. If you want, you could use this calculator
to get an estimate of how many calories you'd need to lose.
Lastly, it's okay that you've been going over points, that's why you have your weeklies to fall back on. Although, if you want to lose more per week then don't use as much weeklies. Personally, I can't lose at the rate I prefer if I use all of my weeklies but I think that's because I have not worked out in a long time and pretty much all of my muscle mass is gone.