Hi Nellie,
Whatever you do don't feel bad about your running times, you are doing fine..give yourself a pat on the back...could you have run 3.5 miles 2 or 3 months ago?...no!....Just keep going, forget about the days when things don't go well...happens to everyone.
As I already know you started at the same time as me, we are pretty similar. I also think I'm slow, but have tried to concentrate on gradually increasing the distance and feeling better about it (apart from the crap days). I managed 5 miles this morning...first time....although slow, but if you had asked me to run that months ago I would have said absolutely no way.
So just keep going, then on 'good days' practice doing a few short bursts of a faster pace, then back to your usual, your speed will gradually increase with improved stamina.
good luck....but keep going, don't stop now you have got this far, think what you have already achieved.
oh dear, have just read this back...I sound like an 'old school teacher'.....I know how you feel though coz on bad days, I am really negative and beat myself up....I have been in a really bad mood all week...but this mornings 'effort' has really cheered me up.
Lyn.